Shoulders and traps specialization. Give those muscles everything you have and train the rest for maintenance.
Train delts and traps 3 days per week and divide the rest of the body into the remaining 2 days.
Monday: Delts and Traps
Tuesday: Legs and arms
Wednesday: Delts and Traps
Friday: Chest and back
Saturday: Delts and traps
I like to do 3 different workouts:
Workout 1 (Monday) is heavy
Workout 2 (Wednesday) is more isolation/pump techniques
Workout 3 (Saturday) is supersets of one heavy movement and one pump movement
The key is to avoid doing a lot of work for the other muscle groups, you wont lose anything in a few weeks. But you need to be able to devote as much recovery energy as possible on the target muscles.
FROM EXPERIENCE… when you focus on bringing up one lift via high frequency training (Smolov is an example) not all of the strength gains can be maintained. Some of the gains are due to neural factors (neurological facilitation). When you do the movement less often those factors will slowly erode and performance will decrease. However the gains due to muscular adaptations will stay with you, these can be maintained more easily.
For example I once brought my snatch-grip high pull from 125kg to 180kg in a bit over 3 weeks (I actually did nothing but explosive pulls for those 3 weeks). When I got back to regular training my high pull dropped to 165-170kg… so a loss versus my peak, but still significantly heavier than my starting point.
If you specialize mostly on hypertrophy, then the gains will stick with you when you switch to regular training.
What type of program to switch to depends on your goals and training experience.