Switching Up My Workout Split – Need Advice

Hey all I’m needing some advice on my split and if there’s any ways I could change to improve it. Currently hitting the gym Monday–Thursday and keeping Friday–Sunday off. My current split:

Mon: Chest & Back, Tue: Shoulders & Arms, Wed: Legs, and Thu: Chest & Back

I like the Mon–Thu schedule and only have about an hour max per session. I have a leaner physique and I’m not looking to bulk or do high-volume work—just something effective. I feel like I’m getting too comfortable with my current split, so I’m wondering if there are ways I could improve or change it. I’ve thought about switching to an Upper/Lower/Rest setup, but I’m not sure if that’s the best option or if there’s another routine that might work better.

Open to adding cardio or abs on any day as well. How would you structure this while still keeping Fri–Sun off?