Interesting. Is it taught that way or is that simply a personal decision (250 is far beyond my knowledge base) ?
I'm not sure honestly, I have never bothered to take that class :shocked2:. I think 35/25 is "officially" added 260ft+. Some of us use it slightly shallower for rock bottom and a little deco padding but its atypical. I only did once and a little playing with vplanner illustrated adequately to me that it was giving us roughly a 15-20% deco time advantage in the 20mins @ 230-240ft range. I.e. 10-12mins on 32/25 was lowered the subsequent 50% and O2 time deco by ~7mins vs just doing those deep stops on 15/55 IIRC.