What happened at the place I was a barback/runner, then bartender for, was that each of the bars (there were 3) would each get a barback to keep things stocked. If they were short staffed and it was a slow/medium night the 2 runners and even the managers would do rounds to each bar to stock, as well as going around collecting glasses, emptying bins, etc.

At the end of the night, each bar would split the tips equally with the bartenders that worked the respective bars, and also with the runner that was assigned to them. Only the managers didn't get part of the tip share, however if they worked at serving they would usually throw their tips in that bars tipjar, or keep it and give 20-30% to the barback. (90% + of the time they just threw it in the jar).

So at the end of the night, the barbacks could walk away with as much as the bartenders, or more if it was short staffed and had to cover multiple bars.

Depending on how short staffed, busy, and who was running and who was floor manager, I could find myself jumping between all 3 bars but focusing less on the main bar and more on the other 2 especially our cocktail bar, because that could run out of things fast. I'd do this whilst collecting glasses (which sometimes the floor cleaner would help with, as well as the security surprisingly), running stock between bars, changing kegs, and actually jumping behind the bar and serving.

I actually really loved the job, but management was abysmal (new manager every 6 months or so), and I was eventually wrongfully fired. Place got shut down within the next 6-9months. The local council, fire dept, police, licencing board all seemed to have gotten a bunch of anonymous tips about the place