I did not post that you should train arms/shoulders the day before chest/back. If you get enough rest after your arm and shoulder workout, it should not hinder your chest/back day.
And trust me, if doing arms and shoulders impede your chest/back workout, it applies vice versa. I’ll predict that on a fresh day, your numbers will be better than they were if you were coming off your chest and back workout.
Not going to fix whats not broken? You sound like the old people who didn’t want to get a HD TV when I use to work at Circuit City. Sure, the old tv works but why not use a better one. Same applies to your program.
And thats not my typical bench day. 6 Reps is semi-high for me, I usually keep my reps ranging from 3-5 and do more than 4 sets. Unfortunately, you can’t get constant results from going heavy all the time so I change up my rep scheme every month or so. I’ll PM you a link or some info that helped me greatly with bench.