I got an RFE — how much time do I actually have, and what if I need more?

The deadline is printed right on the notice — usually 30 to 87 days depending on the form, so don't assume a standard number, read yours carefully. If you genuinely can't gather everything in time, respond with what you have by the deadline rather than staying silent; a partial, on-time response is almost always better than a complete one that's late.