As much as you want, really. If you're happy with the results and it sounds good to you, then you're done! There isn't much point in poking around every parameter if you aren't sure what it'll add (of course, play around with it for practice so you'll know how to utilize it in the future, but you don't need to go into every project with the intention that every parameter must be used).
Whether something is undertuned or overtuned really is subjective, too. What may sound overtuned to you probably sounds great to the person who did it and they're happy with it. If that isn't your style, it doesn't have to be. Just do whatever you like!