Honestly if you can only train for 3 weeks before having to have a week off you probably have AIDS or some other wasting disease
Deloading is for before meets. The only exception to this is when I completely lose motivation and I will just not go to the gym until my motivation comes back again, which is about a week. This has only happened twice for me.
If you're manipulating volume with intensity correctly, you should never have to deload. Every single rep you do is improving your skill in the lift or your skillset as a strength athlete. I can lose motivation because I really can't be fucked do heavy singles that week, so I do something else that helps me advance as a lifter. I can do lat work, planks, dynamic effort, reps, curls, whatever. missing 12 weeks in a year of training where you just warm up on your main lifts and call it a day? Fuck that