I would take Day 4 as off - you're doing upper body 3 days in a row on that split. IMO that's just begging for a rotator cuff problem or elbow / forearm tendonitis - these are things that generally come under "repetitive motion" injuries. Lifters tend to follow the same lifting habits and don't allow a lot of full flexibility / mobility activity to be included. These two areas are usually the first to start cropping up for regular lifters. I can also tell you as you get older these will become your weak spots and they don't really "heal" quickly once they are really aggravated. As you get older, your general ability to "recover" starts to diminish, along w/ repetitive motion type things from sitting at a desk / computer use - this all accumulates into shortened tendons that just don't "get fixed" quickly.
You might also consider this if you're doing a 3 day split - the 4th day always as "Off". Don't worry about how this fits into a 7 day schedule - just take every 4th day off - the reason as mentioned above - you are not doing your smaller upper body tendons & joints a favor by beating on them 3 days in a row.
You can further cycle in an active recovery program by doing the first 3 day cycle as the first of each day's 2 muscle groups "heavy" and the second "light" and then the second 3 day cycle, the second muscle group "heavy" and the first group "light" E.g.
Day 1: heavy chest / light tris
Day 2 heavy bis / light back --- I'm considering this alteration so you're not doing heavy tris & heavy bis back to back
Day 3: heavy legs / light shoulders
Day 4: off
Day 1: heavy tris / light chest
Day 2: heavy back / light bis
Day 3: heavy legs / light shoulders - frankly if you're only doing 1 leg day you can always keep it heavy, or maybe every 3rd or 4th 3 day cycle go light / heavy shoulders.
Or you might break legs out into a ham / glute and a quad day and turn the whole thing into a 4 day cycle, but I'd still put the next day "off".
Recovery is just important. You don't need to be in the gym every damn day - instead for each time you are in the gym, go balls to the wall, but still give sufficient recovery time.
