Having experiencing marine velvet I will never add a fish to my display without a minimum of 45 days in observation. I have 3 tangs that survived that outbreak after I moved them all into copper for treatment and have now been with me for 6,9 and 10 years. I lost more than I saved

Personally I would not skip QT because it's a hassle. A hassle to me is trying to rush a hospital tank set up to treat a tank full of sick fish.
I lost too many fish when I tried medicating every fish I purchased. I'm sure it was something I did but not knowing what I did wrong I decided to switch to observation.
I used it as an excuse to set up another tank

I keep a 40g running with 2 small fish and all my new arrivals go in so I can monitor them. I also use the time to condition my new fish to tank life and get them eating foods I feed.
At the end of the day it's a personal decision and we all make our own choice based on our risk tolerance and experience. I don't recommend not to QT just because I don't because not everyone has the ability to be as selective as I can be when I buy fish. I feel that is the most important step to success and not everyone is able to complete that step so QT becomes more important.
I recently had a reefer 300 fail and used the opportunity to upgrade my observation tank. I know have a 40g complete with sump and reef mat. Thanks redsea lol
My observation tank
PS. I introduced velvet when unbeknownst to me I added a fish that was housed in 1.015 salinty and low level copper. 48 hours after acclimating it to 1.025 and adding it my DT it died and others began to follow.