I don't think there is a tried and true rule of thumb concerning the size or number of holes used. There are too many variables involved.
There is a size difference in laser-drilled holes and tool-punched holes. Juice thickness determines how fast or effecient it can pass through the holes to keep up with the individual vaping. There are differences in the technique of how people pull or puff on their devices. The tank's themselves vary in how tightly they keep their pressure seals, especially the grommet-style tanks. And finally there is a difference in the polyfill used in the different brands of cartomizers, some are more densely packed like Boges, some are more loosely packed like Smoktechs.
I can only tell you what I do, and I consider myself to be a reasonably successful cartotank vapor.
I prefer laser-drilled cartos. These offer consistancy carto to carto. No human error involved for different sized holes, or too deep which can damage the center air tube or compress/pinch off the polyfill to cause inefficient juice movement. Tool-punched cartos invariably warp the carto tube, which can place unnecessary wear and tear on the o-rings of tanks that use endcaps.
I typically choose a single hole for juices that have a typical 50/50 pg/vg ratio. Any juice with more than 50% vg I will use a two hole carto. The only juice that I have had trouble with with this methodology is Boba's Bounty, which is notorious for being one of the thickest juices available. I have even resorted to double hole self-punched both top and bottom with this flavor, and diluted it with distilled water, and still it gives me a stiff pull when vaped. Luckily it is not one of my favorite flavors.
With cartotanks, I do a slow consistant 5 second draw into my mouth. Short hard pulls can force too much juice into the carto and lead to flooding. Dry hits or a burnt taste while vaping means ineffecient and slow juice movement into the carto; some primer puffs (pulls without power on) might help jump start the juice flow more effeciently.
Once a carto has that nasty burnt taste or has had heavy flooding, it is likely a lost cause. There is also the possibility of defective cartos...a bad batch. Boge was notorious for this last summer during "Boge Gate".
There are many threads concerning flooding cartomizers in the tank and cartomizer subforums here. You might gain some additional insight there.