Somebody mentioned that they turn their barrel over when using foaming cleaner as the foam migrates to the bottom of the barrel. Would the same hold true for a liquid cleaner?
Also, many mention leaving cleaner in the barrel overnight. Does the cleaner dry, and if so does it continue to work after it is dry?
Most of the time I don't leave cleaner in the barrel longer than 15-30 minutes but am wondering if this is long enough.

I don't leave cleaner in a barrel over night and I have no plans to leave it in longer than 15 to 20 minutes. I clean with Shooter's Choice and Barnes copper remover. I use a bore snake to start, then run patches through alternated with a nylon brush. When the patches come out nearly white I stop, lubricate the barrel and put it away. It takes me 30 to 45 minutes for a barrel cleaning but I prefer that to coming back every 15 minutes for several hours.

SC and Hoppes say you can leave their cleaner in the bore without damage to the bore.

Barnes containes ammonia which needs to be removed after a few minutes.

But I read somewhere: to remove heavy copper foulings, you may fill up your barrel with ammonia and lock it airtight, you may even leave this setup overnight with good results and no damages to the bore...