You got a ton of downvotes because every couple of pages someone who hasn't taken days out of their life to read the entire thread pops in to ask about how this applies to the marathon, a topic which has been discussed extensively (especially this year thanks to sirpoc's marathon debut). Don't take it personally.
I ran my marathon PB 2:38 last year on a 16 week block of 38 mpw avg, 46 peak (had been doing even less mileage and fewer workouts previous to that). My advice is that this method can't magically make you handle a larger training load than you're capable of handling. Don't view it as a way to do mileage that you haven't been able to do before.
There's nothing magical about the ~30mins of subt time that the standard workouts contain (ie 10 x 3min, 5 x 6min, 3 x 10min). You can start with less and that's productive. Aiming for 20-25min is totally fine. 7-8 x 3min. 4 x 6min. 2 x 10-12min.
Or you can stick to the 30mins now but you really ought to target the slowest paces on lactrace. So for your 2:36 (and maybe you're fitter or you've lost some fitness since then, I don't know), you'd be looking at 5:50, 5:57, and 6:06 for 3min, 6min, and 10min reps. These paces get you above LT1, not near LT2 like we ideally want. But it's about what your legs can handle and what training load you can recover from, which might mean we're not mechanically capable of hitting the ideal metabolic training (yet!). So we "train to train" to get our legs used to the weekly structure and over time we can handle getting closer to LT2.
I personally found that doing as little warmup and cooldown as possible is helpful. For example, you might do 10 x 3min but the first 2-3 reps are essentially warmup. And you'd do maybe a half mile jog before launching into 10 x 3min. No cooldown.
One other option is to occasionally plan a harder day where you're going to do 30mins of subt and target being closer to LT2 than LT1, but then you take an extra day of easy running before you do another session. I wouldn't make the day after the harder session shorter or take it off. You want to practice running the next day to get used to it.
Also beware of the long run. For some people it's not that fatiguing, but for some of us it can be (even when we're going slow). If your normal easy days are only 30-40 mins, then your "long run" doesn't need to be more than 60mins at first. Sounds ridiculous that a 2:3x marathoner can't jog more than 60mins without consequences, but it's the truth for some of us. Again, the training load we can handle has almost nothing to do with our race performance. So be honest about where you're at with training load and you will be able to increase it over time. If science says the benefits of a long run kick in more at 90mins and longer, then that's just too bad for us right now. We don't get those benefits until our legs can handle the load.
The important thing is to find a starting place that you can handle and have patience building from there. Ultimately though, people doing this method like to do harder and longer workouts for a few weeks preceding the taper for a marathon, so they don't follow this method exactly all the way through. But does the method build a ton of fitness relevant to the marathon? Obviously yes. Sirpoc started as a 20min+ 5k guy and did this method for years, raced mostly 5k's, and did only a handful of workouts that aren't prescribed in this method (but aren't even that different or extreme), and ran a 2:24 marathon. So obviously 99% of that ability to run a marathon was from this method. The few special workouts could not have been more than a cherry on top.
The majority of his pre-marathon training was business as usual. Over a 14 week period, he did 8 sessions that were 12-15k in volume rather than the typical 10k of volume. Those consisted of 4 x 3k or 3 x 5k. He did two even longer sessions: 4 x 5k and 5 x 5k. He had one 24k progressive run with the first 16k at ~93% MP and the last 8k at MP. He did two medium-long runs with a continuous 10k subt embedded in one and 3 x 3k subt w/ 1k float embedded in the other. He raced a HM. And he increased his long run up to a peak of 2h23m by adding a bit on each week. But he also noted that this training wasn't sustainable so it was more of a traditional "briefly overtrain then recover with a taper". But I imagine that applies just to the last few weeks where he raced the HM and then did two weeks in a row consisting of two of those bigger volume sessions. The other ~11 weeks I imagine were pretty sustainable despite some 12-15k sessions and the slowly increasing long runs.