Marathon training is usually a one and done approach for me. Pick a target time and hit the workout numbers.
How much value can I gain from focussing on shorter distances and for how long until that starts to make a difference for longer distances?
Is shaving 10 minutes off a marathon more achievable in long distance training or do I need to hit the low 16s for 10k first?
I’m usually too tired for speedwork in a marathon build.