I agree that it should, but I think my whole runnjng attitude has changed since so did a 60 mile ultra in Autumn last year and the mileage was so high that it rely knackered me out for months afterwards. I've in the past always done multiple 20milers before marathons, but I felt like I was champing at the bit in the recent 20 mile race, so know it was the perfect pace for me. I felt like I had everything left to give for that final 10k. Bring on Brighton and PBs for us all!!!
With previous marathons I've put in huge mileage and ended up knackering myself, but I did a massive PB in a 20 mile race a few weeks ago and I know it's because I'm not over-trained for once, but you're right - different things work for different people. It's taken me years to work out what's best for me!
I still say less is more at this point! I think short, fast runs are most useful at this point. Don't exhaust yourselves with too many long ones! I'm going to do a few more 15 milers and that's it (long run-wise) before the big day.