IDK if 14.1 players practice more. I don't know any "pure" 14.1 players, anyway. Nowadays everybody plays rotation games. I have to sometimes play 9 and 10 ball, because that is what most people play, even if I consider them MUCH inferior games to 14.1, and of course the national league system and championships mostly focus on rotation games. The thing is, that the shotmaking you learn playing rotation games will give you lots of firepower for your 14.1, so playing those games is not a waste of time in that respect.
There are certain concepts in 14.1 that are very difficult to practice with structured drills. They are about seeing possibilities in chaotic and unique situations. You can't really practice that. Other than that, there are many drills that will help every pool game. All classic cueball exercises help 14.1 play. I practice running the balls, and several drills I invented myself.
I really practice rotation games kind of half-heartedly. That is, I should probably spend 50% of my time working on my break. I just can't. I don't like the games enough to spend my time on that, so I could possibly be better at 9/10 ball than I am right now. I just don't want to endlessly stand around the pool hall, smashing balls all over the place. I'm happy to shoot a shot I'm struggling with (in straight pool or snooker), or a drill 500 times, but I don't really care about being good at 9 ball, so I don't spend a lot of time on the break. The rotation games are mindless, brute games that have very little subtlety to them (straight rotation being the only exception). If you have a good break and can make the basic shots, you'll be at least half decent at 9 or 10 ball. The whole game has maybe 12 shots to it. If you can make those 12 shots consistently, you can beat anyone on the planet so long as you break well...The people I know who play almost exclusively 9 and 10 ball spend FAR to little time on their breaks. IMO, once you are a decent player, half your time should be devoted to the break. Instead, they are mindlessly pocketing balls without any structure. I guess a lot of people don't have the mental stamina to spend their time practising only 13 shots. It's easier to practice straightpool, beacuse it inherently has more variety to it.
I don't care how well you make those 12 shots in one pocket, it just won't be enough, and in straight pool you will also come up short...So yes, I practice straight pool in a more focused manner, and more often. For rotation games, I mostly work on my shotmaking.
Experience, knowledge etc. are not even really advantages in rotation games. The winner of many tournaments will be the 17-20 year old who just fires at everything without thinking. The races are too short for this to come back and bite them in typical tournament formats. You want to be good at tournament 9 ball? Shoot the 12 shots and practice the break until you bleed. Then, when the tournament comes, shut of your brain and fire at everything. It's a crap shoot anyway, the winner will usually be decided by the break and one or two random rolls.