People SHOULD say it during fights like Lev EX. I rather say it and potentially piss off a caster reminding them, then actually have them forget/not do it and cause a wipe.

"I thought the other caster was going to cast it"
"I've never had to cast it during this fight, it was always another person"

Those lines I've heard soooo much in Lev ex I learned to just say it regardless.