Depends on what it was I did wear diapers 70% of the time. The only times I didn't was during PT, Road Marches, and those awful drug test and staying in the field. Other than that it was standard. I wore Goodnites, Depends, and Tranquility Slimline,
There are a few threads about this from earlier: here, here, and here. There's quite a bit of debate on the advisability of being padded, mostly boiling down to only if you have more privacy.