I've been through a bunch of guns over the years, but the LCP is what I pocket carry now. I use one particular holster that fits every pocket in my wardrobe. I readily admit that's an exercise in compromise, but the consistency outweighs the other incremental factors. I have found the weight of the LCP to be tolerable in all conditions and the snag-free design has proven to me to be a necessity when a compromised draw is required. But, the real advantage to pocket carry performance (IMO) is establishing a proper firing grip before any movement in the presentation is initiated and most guns in most pockets won't allow for this in my experience. You can fudge on this factor at the range (standing upright and square to the target) but I think you're simply cheating yourself.
As to drills and practice, I make no distinction in what I'm carrying and just use my performance with the LCP as a comparative standard against my service pistol scores. I do a fair amount of WHO shooting, outer limits stuff like steel at 50-100 yards, and I emphasize head-shot drills at 5 yards and closer. When shooting established drills like The Test, 5x5, etc, I simply modify the COF to fit my limited magazine capacity. At least twice a year, I also use my LCP to shoot my agency's annual qualification COF which consist of 50 rds; position shooting back to 25 yards day time, and 15 yards at night under conditions of ambient light, flashlight and headlight/emergency lights. It's not a tough COF by any stretch, but it's representative of what's used in the LE community and I generally score in the high 90's and on a good day will shoot it "clean".
Anyhow, I posted all that to make the point that I think it's important to know what you can and can't do on demand, but that should apply to any gun - not just a pocket gun.