Schultzy is your man here. I bait in the spring. But to answer your question I filled my bait...... it lasted all season. I would have refilled if it ran dry though. All in all I had 500lbs of bait then 70 gal of grease.
How many barrels can you get? Like I said I run 2 per site and last yr ran 2 sites. This yr I'm gonna run 4, maybe 6 depends on how many guys want to hunt. I want 2 per hunter. I like small holes in the barrel...... that way your bait will last longer. You wanna make it so they can get to the bait and without too much work or they will move on. I do 1-2" holes