Tempo Run Distance

I'm no expert but I think that both have a place in your training. Perhaps earlier on in the training you do the longer ones (60-90mins) and then as you get closer to the marathon you decrease the time and increase the pace. I like to go something like: 15k, 20k, 25k, 25k, 20k, 15k, 10k and then a weekend with no long tempo and then race. My 2 cents anyways. If I am racing then the race replaces the long tempo. I also do a shorter tempo run each week before I do a hill session.

Don't think in terms of "tempo runs". Think in terms of "time trials". Going for a 3 mile tempo run? Run it at 10k pace. Going for a 6 mile tempo run? Run it at half-marathon pace. Going for a 12 mile tempo run? Run it at marathon pace.

Alan

For marathoners, the "typical" weekly tempo run is at half-marathon pace and should be 5-8 miles, depending on where you are in the training cycle. Some runners like to add recovery intervals and go further, like 3 x 5K with 2-3 mins jog inbetween. Besides the training adaptations, they have the effect of making marathon pace feel easy.

Goal pace runs are typically longer and less frequent. I think the typical range is 12-17 miles. Once a month is probably sufficient to develop a feel for the pace. Most runners substitute long runs to do a GP run which is a few miles shorter incl. warm-up. That way they don't sacrifice a tempo or interval run. Another thing to do is to peak on long-run distance 6-7 weeks out and as you gradually shorten your long runs, you start to add progression. Different things work for different people.