I meant to put this in my first post. Problems at full extension on push up holds would suggest a serratus anterior weakness to me. That's the first thing that comes to mind, anyway. Scap push ups are a good start and DB protractions take it to the next level... Under Shoulder Saver 2 in the following article - worth a shot. Personally, I will always do scap push ups in my warm up and every couple of months include DB protractions in my program.
Also, when I'm strugging for time I go for a super set option on a couple of exercises, normally the ones towards the end of my work. Sacrfices load, makes you sweat more, but it get's it done in less time. In your case, an example would be,
Lunges alternated with Pall of Press. Really, you just alternate exercises, set by set. So, lunges, then over to cable and set of pallof press, then lunges, then pallof press... So, you would do 6 straight sets instead of 3, then a rest, then another 3, for example.
Another thing I do is get bigger bang for your buck exercises and incorportate it into the same principle. For example, instead of throwing in something else that will hit my upper back for higher reps, THEN some external rotations then some direct lower trap work.. I will do Face pulls With external rotation (change hand position) supersetted with straight arm lat pull downs...
Or seated DB cleans super setted with prone trap raises... both options hit the external rotators upper back a long with direct lower trap work inbetween sets, all in around the time it normally takes me to do one exercises
Just some food for thought.