It looks like a reasonable enough template, assuming the exercise selection is sensible.
To answer your question, no, you shouldn't mix up the intensity/deload phases for each body part. The idea is to deload the entire body. If you're going light on squats but heavy on deads, that's not a deload at all - you're still loading.
If you feel really beat up at the end of the heavy phase - well, you should do It means you're doing it right. A loading phase should finish in you REALLY needing a rest. This allows the rebound during the deload period to give you the gains. This is why it's working for you. If you find yourself finishing a loading phase without feeling like you HAVE to rest, then you probably won't get anywhere near as good gains. Suck it up and enjoy the 3 week deload