According to Osho, there is a limit only when your questions are authentic—rooted in your own being. True inquiry resolves itself and eventually falls silent. But borrowed, secondhand, 'scholarly' questions are endless, like a parrot repeating words without understanding. Shift from accumulated knowledge to lived experience; then questions finish and clarity remains.
If your questions come from your own heart and life, they end in understanding; if they come from books and others, they never stop.