The subject of bridges in pool is poorly covered in the litterature. The best I've seen is a complete list of bridges with some rudimentary instruction on how to make them. Few people take the time to point out the absolutely vital part a stable, quality bridge plays at the higher levels, where even a quarter tip mishit or less can lead to absolute disaster. And that's just in the vertical direction, side to side, even a hair can cause you to miss the longest shots. I was helped tremendously by some vary basic carom instruction, where I realized that my closed bridge, though better than many others, had quite a bit of potential for improvement. The very fine micro-adjustments to the finger positions that I've since applied to all my cue-games has tremendously cut down on mishits on the cueball. A good, solid and immovable bridge helps in two ways: It makes the stroke itself more stable, and it helps to reduce indecisiveness. When your bridge is at the correct height and firmly planted, it's not so easy fall victim to last minute adjustments, which in most cases are wrong.
When I see people getting up to about a C-level of play, I think the bridges are huge factors in their advancement or stagnation. Most players never learn the proper, non-jacked up rail bridge. Which is sad and surprising. Most people have terrible closed bridges, which are neither tight enough, properly formed or even stable enough to allow high level play. Their open bridges are usually not good either. Their fingers are not spread out enough, their hand/wrist is not the right angle for them and often the thumb is not brought to the proper place. You sometimes see recreational players with the palm raised off the table, their hand tilted like a karate chop. It's torture to watch this crap going on, but what can you do, you can't help unless they ask, and most never do. These are extremes, but I'd say below A-level, 99% of pool players bridges are severely deficient in some area or other. Carom is a completely different story. They seem more open to technical instruction.