I used to be fanatical about it,but now i don't do much. My plants don't touch the walls and i don't use foliar sprays, so it stays clean.
h2o2 breaks down really fast in light and isn't a very good sanitizer, to be honest. The 35% stuff probably works fine, but 3% needs 10-15minutes on a non-porous surface to disinfect it. If it dries up, which is almost certain the case, it won't complete the job.
if you had an infection of some sort... good to put in a little more effort. Just use some 'bleach' and dilute it as instructed on the label.