[bazzargh]

Depends what it is, but commonly - no. There's been research on this:

http://mcis.polymtl.ca/publications/2013/msr_jojo.pdf

What percentage of submitted patches has been integrated successfully, and how much time did it take? Around 33% of patches are accepted. Reviewing time has been dropping down to 1–3 months, while integration time steadily has been increasing towards 1–3 months, bringing the total time to 3–6 months.

That's based on 8 years of data.