Running the numbers

I put all of my runs since Jan in a spreadsheet to try to extrapolate where I'll be in a few months. Here's what I found:

1) On average I've been adding 15 minutes of running to my weekly total each month. So for example, if I'm at 35 minutes per workout or 4 miles, 3 times a week, when will I be at 5 miles per workout? Ans: about 7 weeks. But then again, I don't know. It could happen faster, or my recovery and the improvements may slow down or stop altogether or even reverse for that matter. It will be interesting to see what the curve looks like in a couple months. One thing is for sure though-- 8 weeks from now I won't be running 7 miles. I'm used to measuring improvement in miles per week.... and I think this has been one of the problems-- it's difficult to apply my expected improvement in miles per week to each workout (.4 miles/wk divided across 3 or 4 workouts?) Hence, the weird units, minutes per week per month, but even these units are difficult to apply-- 1 mile/workout/7 weeks-- there, that's better.

2) I've run a total of about 85 miles since Jan. Shoes are lasting a long time-- big plus.