Thanks Gaz.
I usually do a heavy set that I can only do between 3-5 reps every other month, depending on the exercise. I think i'll spread them out every few months as well.
That is what you meant by 3's and 5's, correct?
Yeah, like going for records on a set of 3 or 5 reps.
Honestly a lot of it depends on how you feel. Lately i've felt great, and really pushed myself and made PRs every week or so - but im only recently getting to my true max. I've obviously gotten stronger, and doing PR attempts at weights i thought would be maximal effort, but weren't.
After a few weeks of this i hit my actual maxes, and could tell this was the case because they were absolute gut busting sets, and i've subsequently gotten very tired latelty, haha

.
Only do a max set:
If you haven't done one in the last few months - to avoid over-training and injury.
If you think you can improve on your old max - because if you can't, there's no point stressing your body that much.
If you feel absolutely 100% perfect condition - if you go into it tired, ill, fatigued from previous training, or not with it mentally you'll just waste it.
This goes for singles, 3's, and 5's i think. So planning your training cycles, taking extra rest before and after a PR attempt, and keeping an eye on your condition are all really helpful tools in deciding when you should max out, and on what exercise.
Once you hit that maximum poundage, start your next cycle light and work back up to it.