Reg cleaning requirements are somewhat determined by the type of reg. My first stage is an environmentally sealed diaphragm, so cleaning requirements are a little different, as water shouldn’t be able to get in to any moving parts.
At the end of the day, I set up a big bucket filled with water and a bit of Salt Off (unless diving in fresh, then just water). Tanks are positioned next to it. Regs attached, and tanks pressurized. 2nd stages and computers, knives, etc. soak in the bucket. First stage and tank get rinsed thoroughly with the hose. 2nd stage purge and inflators are pressed a couple times. Then I leave it to soak while I clean the boat.
When the boat is done, I return to the gear that’s been soaking. Everything gets rinsed off again, including 1st stages and tanks.
BC used to be the most challenging, until I got a Zeagle. The outside of the BC gets dunked a few times in the bucket, then rinsed. Garden hose is attached to Salt Off mixer, which is attached to inflator corrugated hose. I run with Salt Off solution until bladder is full, then switch to plain water. I cycle each dump valve several times, then let drain and hang up. Usually the next morning, I’ll dump remaining water from lower dumps, and put away.