This thread got me thinking, especially
@BurhanMuntasser and
@Graeme Fraser's posts about dive ops and LOBs requiring a simple 'check' dive to dial in weights etc. even for experienced divers. The LOB I just did in January didn't do that--our first dive was a wall dive to 110 feet, because they wanted to start with the deepest dive--and it was fine but perhaps could have been better.
I wouldn't have thought I would need a checkout dive. That first dive of the trip was Dive #93 for me after first getting certified only 14 months before. I was diving my own gear, including the same wetsuit I used at home, and I had last dived just a few days before the trip, after getting my reg serviced, to make sure everything was good to go. I had dived to those depths a few times and felt comfortable there. Sure, my buddy was a guy I had just met, but we had a guide; I dive locally with instabuddies and no guide all the time. And yet, I wrote in my log book, I felt "uncharacteristically anxious, like I wasn't getting enough air."
After the dive I adjusted the knob on my second stage to make it breathe easier, and my second dive was better. Maybe the knob got bumped in my luggage and I fixed the problem. Maybe I was just nervous, and either the placebo effect of doing something about it, or just the natural rust-scraping of getting the first dive out of the way, calmed my nerves. But it occurs to me that, had I rented or bought a new wetsuit of a different thickness for this trip, I would have had to make at best an educated guess as to how much weight I needed, and might have gotten it wrong and been struggling with that on top of whatever else was going on with me. And while it was all fine in the end, maybe a check dive in the beginning wouldn't have been the worst idea either.