D&D 5E Major Image (Spell): When should a creature use its action to examine something that it believes is real?

[jgsugden]

You may wish to note one issue related to that investigation check: If you suspect it to be an illusion, you have the choice to use an action to get a chance to discern it as such with the investigation check, or you can interact with object to toss something into the illusion to reveal the truth of it for sure. If you relegate the investigation check to only an active check and only when the illusion is suspected, you're really minimizing it.