Depends on the dive. . . . I went to North Carolina to do some wreck diving on some old wrecks from world war II and you want all the bottom time you can get since some of the wrecks are in the 100-130ft range. We brought 28% steel 100hps for that exact reason, specifically when we dove the German sub that sank there. This sub lives right at the 110ft mark or so if memory serves me correct and time flies when you are trying to check the entire wreck out at those depths so yes, an extra 3 minutes was definitely worth it for that dive. I do recommend 100cu tanks for those dives because they are exciting and you can suck air down pretty fast when taking pictures and such.
I'm not usually one to do everything possible to squeeze an extra minute of bottom time, but I have to agree with you on that one. The boat ride out of Morehead City is almost three hours to reach the U-352. All so you can have your few precious minutes on that wreck.