That barrel has one hole in it, the one you can see. The bears, all sizes, will just lay next to it and pull one piece out at a time. Larger holes mean I have to drive out there and bait more often. They will empty it in a night with no problem. I'd say, on average, there are 6-10 bears using the bait site on a normal year. They go through bait quite quick. I do add plenty on the ground as well, the barrel with a small hole ensures there is always something at the site until I can hike more in.
A good strong call scent is key, for me anyhow. The majority of the bears we shoot are not the "regulars" that frequent the bait daily. We typically end up shooting bears that happen to find the bait for the first time while we are sitting, which can be attributed to either a sow in heat or the atrocious call scents I use. We are along a river corridor that allows for new bears to show up at any time since it's a natural travel route. They aren't coming cause they know there is food, they are coming to inspect the scent we use.
This year, I won't be using a barrel as I've had better results (others have too) without one, especially when it comes to getting brown/grizzly bears to come in on a regular basis. Since a Grizzly is my goal this spring, I plan to go the route that I've found to work best for them.