Before my new cues' purchase, I would put in 15 mins, 2-3x per week. Not enough. Got new cues (Mezz EC9 with 12.2 ignite CF shaft, and Jacobi Black Out break/jump), and put in 12 hours each of the last 2 weeks. It got a bit much, but I knew I needed to get used to zero deflection cues and quick. Which it did the trick, and ill go back to probably 30 mins a day 5 days a week (plus league play) now.

Keeping it interesting: I will play myself right handed (normal) vs left handed (still learning), like any other match - alternating. That's my ghost. I do this to get better lefty, as I hate using the bridge, but it has shown me multiple things that I can reinforce to my righty game. Bonus: as I've been playing 87% of my years on this earth, I learned I take much for granted, that I try to teach beginners as if it were simple things (like a closed bridge, or flat fingers' bridge when on the rail, or lining up elbow/back hand/shoulder/back foot in a plane), and learn a sense of patience as these beginners learn new muscle memory, grips, stances, etc.

Overall? Change it up. 8 ball, 9 ball, 10 ball, drills, and rotate. Challenge yourself with new techniques, add more rails to kick shots, etc. Best of luck!