In Bridge, Is "ruffing" a good enough reason to postpone drawing trumps?
There isn't really a single answer to this; when to draw trumps and when not to is probably the area where most judgement is called for, as opposed to applying rules.  You have to balance the probable gain from ruffing early against the possible loss if the opponents ruff your winners later (or, of course, over-ruff).  I realize this isn't necessarily helpful, so here's a list (non-exhaustive) of factors that weigh against taking out trumps:

You can use a trump in the short hand (ie one that would be swallowed if you take out trumps).

You have enough high trumps to ruff high without compromising control.

You have a long suit that can be established by a ruff or two (in which case of course you must take out trumps after the ruff).

After one or two rounds, the opponents have the high trumps: they're going to win anyway, no sense in letting them take your trumps as well.

You can see that normal play, such as taking out trumps, will leave you one trick short, so a gamble will give better returns than normal in the score.