acclimating time?

[Lance]

I am a little confused as to acclimating time for new specimens. I've been accllimating new fish to my QT for about 1 hr., adding about 1 cup of QT water every 15 mins. For inverts I add much smaller amounts of water over a 2 hr period. I haven't lost anything, but am I just lucky? I've read that marine fish should be acclimated for 1 hr to 4 hrs. and inverts as long as 6 to 8 hrs. My LFS does 15 mins. for fish and 1/2 hr for inverts. What gives? What works for you?