I do Ian’s arms routine twice a year and for shoulders I just do a giant-set of all the lateral raises. Grab some DB’s, say 20’s and whichever is your weekest lateral (front, side or rear) and knock out 8-10 reps, then the next strongest for 8-10 then the strongest. For me that is front raises, side, then bent over rear lateral raises. I do one warm up with 10’s then hit only 1 set with 20’s or 25’s. Trust me they will be plenty heavy by the last set! Works for me.