My thoughts:
5's: Should always be a part of any training program. Can be used for sets across on volume day. Can also be done as a 5rm on an intensity day. Can be used as back off sets after heavy singles.
3's: Also a good rep range to get you exposed to some slightly heavier weights if you have been using fives for a while. Triples always seem to die out quickly, so I have never had success using them over sustained periods of time (i.e. 8 weeks of triples on ID on the TM). Good for a few weeks of tapering after a long period of 5s or as part of a rotation with other rep ranges
1's. I love them. Singles across are always a good way to unstick a lift and expose the body to heavier weights. They do a good job of "making your sets of 5 feel lighter." Obviously max effort singles are the best way to test strength but should be used sparingly unless you are rotating exercises around.
8's: I'm playing with them right now as part of my regular programming for my primary lifts. They seem to be making my sets of 5 days much easier.
10-12: the range I typically use for assistance work for lats, triceps, etc. In combo with heavier work in the 1-5 range, they make you bigger. Good range for back off sets with the primary exercises.