Well, some people are different I guess. Also, it is reasonable to believe that most of the time that you guys are jumping, you are jumping to mileage numbers that you can't handle. And the reason, you jump is probably because deep down-- you feel that you can't handle, so you want to try. Jump to something you feel like you can handle, then if you can, go higher.
My last 6 weeks have been:
0,0,31,85,84,85, Feel fine this week, knocked the morning run out of the way today. I didn't jump to 100 because I didn't feel I needed to. Maybe when the urge strikes me. But I feel somewhat comfortable, with this volume. I can be consistent.
One more thing, DO NOT try to jump up your mileage "doing singles" then complain about not being able to handle it.
Lets say, a 60 mile per week runner, does a 13 mile long run. Then decides to go to 85 miles per week on singles. Not that big of an increase in my book, benefits will outweigh risk, so take it. But NOT ON SINGLES. That is basically a long run every day.
I do about 11 runs a week.