Oddly, clusters don't really seem to be an issue for me, not saying they don't happen but I can't remember a time when I thought - damn, I need to change something because of these clusters. But, I did start paying more attention to them. I've got a couple of people that come over and play and when they have a cluster and don't address it early and I ask about it they say "well, I was going to shoot this, then that, then the cluster". Clearly, that rarely works out for them. The importance (for those reading) is to get the cluster as SOON as you can. There are times when it's possible to save a little cluster until later due to ball layout, etc. but whenever possible - get that cluster taken care of early, if you can't control the CB to minute levels then you don't know what's going to happen when you break it out. When shooting clusters look for key balls after the break out AND don't bang clusters! That is the number one killer of runs, hit that cluster JUST hard enough to break it out and leave yourself on another ball. It's like bringing a boat to the dock - how fast should you go? How much damage are you willing to accept?
Balls on the rail are the same. Have a ball locked on a rail near a corner pocket with another OB blocking the close corner, get that blocking ball out of the way soon and get back to that rail shot off a shot that puts you perfect for the rail. Don't save the blocking ball until second to last so now you have to go 3 rails to get back on the rail ball and definitely don't play it long rail, across the side pocket, if you don't need to.
Honestly, at my peak (low 600's FR) I thought BIH was kind of cheating but then I just kept going back to my original thought process years ago - if I can't run a 300 with BIH then why should I change. From there it just became a consistency thing, every score I've ever recorded is with BIH, why change it?
And this game really did make it sink in that the difference between being on TV (e.g. being a pro) is all about consistency and the right decisions (decisions are more relevant to match play).