Should you prioritise a fast 5k before going longer?

Yeah get a fast 5k first. It's easier to train for, and your half marathon time will improve just by you doing 5k training.

Focus on the 5k but keep the milage up. Do longer reps at 5k pace (800, 1000 repeats) to work on speed endurance, 400s and such for speed along with tempo and long runs for endurance. While it's possible to run a good 5k on lower milage but working on endurance and speed now will be helpful down the road when you move up. Also the 5k is like 95 percent aerobic so you still need to be very strong aerobically

Will seem counter intuitive - but keep your 50 mile/week but run slower most of the days. If you are running that many mi/wk and not breaking 20, you probably aren't recovering day-to-day especially if you are doing workouts too. Get a HR monitor so you can get a feel for what each zone feels like. I struggled to break 20 all of last year but i was out hammering everything thinking that's how you improve. Now since the start of spring, i have been running around 9 min/mi for basically 5 runs a week and punctuate the week with a couple high volume threshold (zone 4) workouts (e.g. 8 x 5 min or 5 x 2k with 60s recovery). I just ran 18:47 recently, and the only VO2max (zone 5) workout I did was a single session of 3 x 2k at 6 min/mi pace with 3 min rest one week before that 5k. I didn't think I would ever be able to break 19 min before I learned how to train, and I did that on a night that was 84F and 60 dewpoint, making me think I can get under 18:30 this fall without too much additional effort

You should prioritize spelling.

Thanks for the (sensible) replies.

Dont over think this .When I increased my weekly mileage all my times improved.I had a 21 minute 5 km time .One month out from my first marathon post Covid lockdown I easily ran sub 20 min 5 km with no speedwork just the extra mileage

Swimmers need to show minimum swimming ability freestyle 50 yards or 50 meters before moving up to longer events. Don't you believe it is best to show minimum proficiency at shorter events before racing longer events?

In my opinion yes, I always used the 5K as a way to test my fitness.

I average 40 mpw and do a lot of parkruns. Then when it comes to the marathon I up it to 60 mpw with an additional long run.

Yes. Definitely yes.

You'll be able to handle the volume of workouts much better (which means less injury risk), and you'll be improving your potential at the longer distance.

There's a tendency for people to want to rush ahead to the longer distances (half mara and mara) because said distances get you more likes and kudos on social media.

However, improving your speed will make you a much better runner overall, regardless of what the general public acknowledges.

You're a hobby jogger. Focus on what you want. If you like 5ks, focus on them. If you like marathons, focus on them. Or don't really "focus" on either one and run a random combination of both.

It's not like someone's going to say, "well done, good and faithful hobby jogger" if you break 4 or 3 or whatever in the marathon. Or if you break 20 in the 5k. We're all just racing for fun. So do what's fun for you. If you find any of your race times "embarrassing" then you're missing the point.

I assume based on this comment that you are not doing intervals and tempos? When one's goal is to run fast, some of your runs need to be fast.

I'd recommend that you forget the 30k runs (!) for a while and focus on getting faster with intervals and tempos. Unless the runner is incredibly fit, a 30k long run is going to hinder your interval and tempo training.

Forget the marathon and focus on getting faster first. Better yet, forget the marathon, period.

You probably need to adjust your training. Volume is quite high for your times. How many runs per week do you do? Pace?

Speed is usually neglected, just some strides or hills can be very helpful.

don't overlook 440s and 880s. they may be your best distance.

That’s the old school mentality, getting faster in shorter distances before moving up. Now people jump straight into walking Marathons as their first race.

When I was training for my first marathon, I found that my 5k times improved. If you are just running the marathon to finish, focus on the marathon. If you are running a marathon with a time and pace goal, make sure you add in speed and endurance. That's way you are still doing 400 repeats in marathon training

I noticed this too, the way the OP was written, it appears their half marathon training did not include intervals and tempos.

Definitely ditch the 30k runs, keep up the 40-50 mpw and do tempos and intervals. The 5K and half marathon times will most likely improve at the same time.

If you look at the careers of nearly all top level runners you see that they started in high school, spent years racing the mile, 2 mile, 5 km cross country, then moved onto college where they raced at distances from the mile to 10,000 meters. If they moved to the marathon it was after graduation and with years of shorter, faster, racing behind them. It's very hard to find someone really good at longer races who started off with a handful of 5 kms and then a jump to marathons and half marathons.

If you want to get as fast as you can at longer events I'd say to imitate this approach. But this is a long term approach best suited to someone who is really serious about the sport and is willing to spend years taking short races seriously. Most of today's runners don't seem interested in spending three or four years working up to the marathon. They seem to want to run one as soon as possible. And that's fine. None of them are earning a living from their races.

But the answer to your question is that this is not the either/or thing it's often presented as and you can train for longer events AND improve at shorter distances as well. NOTHING improved my college track performances as much as training for the marathon did. All that meant was running a lot of miles on top of doing some intervals and short races.

Personally for me, I didn’t really feel as though I raced a 5K well until I mastered the 8K. I struggled with getting out fast and managing that.

Yep, this.

You also gotta do what makes you happy. Most of us are not going pro so if you or your friends like the longer stuff then train for that. But it's absolutely right that the faster you get at 5k/10k the better potential you have for the half/full. The problem for a lot of runners are that they do mileage for the 5k/10k but race longer than that. So spend time developing speed. That'll help you build your base & chase faster times when you turn to the longer stuff. When you do train for the longer stuff, put in some good miles & the equivalent times will come.