These are great general questions that are the core of programming.
In this situation, the problem with her press is too little stress. She did 3x5 on the press (or 5x3 later) for 1-2x a week for a while on her LP, with success. This level of volume and frequency was stressful enough to drive adaptation. Now, with the same level of volume and frequency, her press is stuck. The solution is more stress.
In that case I think you’d be fine to move on to more indernidiate programming. You don’t necessarily have to wait until she is missing bench reps too. Though what you’ve already suggested should work fine for a few weeks. You’ll still want to move on to a more stressful program soon.
I recall from one of the Barbell Logic Podcasts that once one comes close to stalling at 3 sets of 5, to add weight then do 5 sets of 3. Then the next workout keep the same weight and do 3 sets of 5.
You could also try something from Bill Starr's article http://startingstrength.com/contentf...ress_starr.pdf. On page 4 he talks about doing 3-6 sets of 3 reps with one back-off set of 10. A conservative approach might be to:
Monday
Squat
Press 3 sets of 3 and 1 back-off set @ 80% for 10.
Deadlift
Wednesday
Squat
Bench
Deadlift
Friday
Squat
Press 4 sets of 3 @ Monday's weight and 1 back-off set @ 80% for 10.
Deadlift
Monday she would press 5 sets and Friday to 6 sets with the back-off sets and then you would add weight on the following Monday and start all over starting with 3 sets again.
She would be increasing her volume slowly and also she would be pressing 2 days a week.
I agree that if the goal were to “unstick” the press then decreasing frequency wouldn’t be a great idea. I suppose the goal here was to mainly exhaust LP on bench while letting the press go up as a by product of the bench going up, and through the slightly increased volume of pressing.
Jordan has suggested on FB that pressing 2x/we and BPressing 2x/wk isn’t incompatible, and it’s what he suggests.
What I suggested there was:
Monday:
Squat: 1x3@8, 3x5@8
Bench: 3x5
Press: 4x5@8
Wednesday:
Press: 4x5@8
Deadlift: 1x5
Light Squat
Chin work
Friday:
Squat: 1x3@8, 3x5@8
Bench: 3x5
Chin work
He hasn’t commented back on the pressing setup though he indicated that he wasn’t sure what I was doingwith the squat setup (a top set followed by back off). In any case, he doesn’t seem to have indicated that BPressing and pressing back to back is a bad idea. Wednesday will be Press priority day.
Once a week pressing in the middle for 5x5@8 would still be a small volume increase over a two week period although slightly less than the week in which the press was done twice. This, combined with increased bench volume and frequency by doing it twice a week consistently should be enough to get the press moving even though it's 5 fewer reps than weeks where she was pressing twice.
If you wanted to press+bench twice a week while finishing the LP, it might be prudent to do both on Friday to allow for more recovery since Monday's presses will be fatigued after benching and wednesday's presses will be more fatigued from having done both 48 hours ago.