Any advantage of doing heavy weight/low rep workouts and high volume/low weight workouts in the same week?
If you're doing a push/pull mix or upper/lower split, then, yes, otherwise, I wouldn't see an advantage to it.
A periodize 5X5 has you do 6-8 weeks of 5X5, a week of 'deloading' - light weight/high reps and then 2-4 weeks of 3X3.
Give chalk a chance.
49 years old
As long as you aren't overtraining I don't see any problems with it. In fact, isn't that concept common in many bodybuilding routines.