My league age 13 YO son, who has been playing catcher primarily for the past 2+ years, and taken a fair amount of catching lessons has been essentially taught to keep his hockey-style mask on pretty much all of the time, EXCEPT for relatively high pop-ups, which you can generally tell by the sound and initial read.
In All-Stars this past Summer, my son always kept his helment on, and the other catcher seemed to flip his off constantly, as in say 15-20 times a game vs 1-3 times for my son. Seems to be a different approach, yes, you can see better with the helmet off, but getting it off takes some small amount of time and, over time, can be hard on the helment itself. Just my 2 cents.