The easiest way to train your monsters without them getting tired. Put in various ways for the level of the gadget you decide to use:

LEVEL 2
Week 1: Level 2
Week 2: Level 2
Week 3: Level 1
Week 4: Rest

LEVEL 3
Week 1: Level 3
Week 2: Level 1
Week 3: Level 1
Week 4: Rest

LEVEL 4
Week 1: Level 4
Week 2: Rest
Week 3: Level 4
Week 4: Rest