Prioritise full-body compound strength, explosive and rotational power, grip and neck strength, and positional trunk strength. Two to three concise sessions per week is usually enough alongside heavy skill training.
Begin with a power movement: Rotational throws or trap bar jumps, 3 to 4 sets of 3. Follow with a lower-body strength lift such as a back squat or trap bar split squat, 3 to 4 sets of 3 to 5. Then an upper-body pull such as chin-ups and a press such as the push press. Finish with grip, neck, and trunk work.
Dead hangs, farmer's carries, and towel-assisted pull-ups build the sustained grip endurance grappling actually demands, which is different from maximum crushing strength.
Landmine rotations and medicine ball side tosses develop rotational power. Pallof presses, side planks, and suitcase carries build the resistance to rotation that keeps you in position.
Two sessions of 30 to 45 minutes a week supports skill training; four long sessions competes with it. Use low reps and full rest so the sessions build strength without accumulating the muscular fatigue that ruins the next day's training.
Reduce volume substantially while maintaining intensity. A short session keeping one heavy lift and one power exercise preserves strength without adding fatigue. See Principles of Strength Training.