That magic number

I think I've mentioned my magic numbers before. So far this has been true. If I can swim 17 or 18 100's on a given interval then I can knock 5 seconds off the interval and swim about 5 100's on the faster interval. I've done this several times already. A year ago I was working on 1:40 two years ago I was on 1:50. When I started swimming on a 1:30 interval I thought I had finally hit my limit. After all there has to be some point where I won't get any faster. I'm not in danger of setting any world records here. But it looks like I'm going to be able to do it one more time. next week or the week after (if I wuss out) I'm going to have try a 1:25 interval. I should be able to do about 5 of them. (probably)