I haven't changed my routine in years. The only that I change is the technique. Like one week, I'll do straight sets. The next week, I'll do pyramid sets. And then another week, I'll go for high reps with lighter weights. And then another week, I'll go for low reps with heavier weights.
But other than that, the exercises and the exercise order have stayed the same.
MON - chest, back (upper)
TUE - rest
WED - shoulders, arms
THU - legs, back (lower), calves, abs, forearms
FRI - chest only
SAT - shoulders, and some arms
SUN - rest