I did it for years and it becomes instinctual. I wouldn't know too much what to say about it except you have to train brutally hard if you want to gain and be the strongest you can, but you can't do it forever. You'll have times in which you'll naturally want to reduce the volume. As an example, when I was training for powerlifting competitions, as I'd approach closer to a competition, I'd always reduce the volume and number of assistance exercises and increase the weight on the bar instead.
Its also worth noting that I don't think that overtraining should actually be the goal. Chronic overtraining can happen if you train to hard anyways. So because of that, it is my belief that you should train as hard as you can and put the amount of work in that is necessary to achieve your goals, then back off on the volume when necessary.
And that brings me to the topic of the long term. You'll notice that competitive athletes will sometimes train harder than ever when competing and do what ever is necessary to be the best they can, but the reality is that training like that isn't healthy. If you're a regular guy who wants to be healthy and continue to workout for decades until they are old, you have to learn to pace yourself. So what it really all just depends on is what your goals are, competition or not.