You can do Max Strength phases during unloading weeks. You just have to either adjust the weights or volume (sets/reps).
So, yes, weights should be altered during unloading weeks. Just don't alter intensity. If anything, bring the intensity up a notch but drop the volume.
Maintenance is a phase that should be used during peak season. The difference between maintenance and unloading weeks is intensity. Maintenance intensity is lower but the sets/reps schemes are pretty similar.
That's what I know. Would anyone else like to chime in?