What is a preferred time limit for giveaways?

US peak traffic? Probably any time between 12pm and 7pm -8GMT. (using pacific time)

i think one day is ideal so people who are asleep get a fair shake but its up to the gifter if they want to do a quick 1 hour lightning giveaway

Personally I prefer the one hour giveaways.

10 min giveaways

I like 1 hr giveaways

Personally, I think 1 day is enough. It gives people globally a chance to enter.

I like 1 hour giveaways but most of them happen when I am asleep. Put up some Aussie quicks by all means! :D

I like the shorter giveaways. Any time is fine; I'm someone who checks at different times. I've seen some very short giveaways, and I like the idea of them a lot (10 minutes). I think an hour is the sweet spot.

I do 1 hour private giveaways, keeps it short and not that many people so the true users have a chance to win and not some random leecher.

I like the one hours too :) Better odds. Still haven't won yet though :)

I too like the 1 hour giveaways :)

I like the 1 hours

I like the ones which are short XD. But depends on price of it.

I generally do 1 day minimum, for my giveaways

It depends by games

I'd say one hour giveaways, whenever you want. This way people who enter will be happy to have found the giveaway and people who don't see it won't be annoyed by the fact that they missed it or that it had too many entries. As for the time, I think the userbase is widespread enough to have a lot of poeple on at any given time, so imho it's not really a problem (usually shorter giveaways are made to limit the number of entries, and making one during peak traffic because it's when there's peak traffic would kind of defeat that purpose).

Depends by game, I'd say 1-6 hours for inexpensive games (<10p) 6-18 hours for mediocorely priced games (10-30p), 12-48 for higher priced games (>30p) and 48+ hours for Pre-orders.

EDIT: If you just want an example which fits all (except pre-orders): 6 hours. You won't hit too many users for it to become crowded too fast, and it rewards active and semi-active users. (Along with some random passerbys too, but that's beside the point)

3 weeks is ridiculous

It should be what ever you want.