I've been doing that since day one of my flying probably to the point of over-squelching (as in frequently), but I had a little bit of background of radios so I know there can be issues.
Didn't realise it was ever taught... and with the advent of auto-squelch I'd say many would not bother testing these days. When using the G430's I usually like to give the Volume two quick presses after changing to check the volume level- similar idea.