Bandsaw tuning often takes on the guise of a black art. With tracking, drift and wander there are usually multiple adjustments that impact them and often when one finds a particular adjustment that works it becomes their holy grail to fix all the woes, you see it with everyone including the experts. BTW all the following comments are directed at crowned wheel saws since flat wheeled/tired saws behave differently and require a moderately different approach. In the past 20 or so years I can only think of one saw I checked coplaner on and that was a PM 141 that I bought where the wheel had been rubbing the upper cover and the axle and upper wheel had been abused and literally bashed together in a way that made them impossible to separate without destroying them, I checked coplaner to see how far it was out from the factory settings to see if I thought I had a shot at tuning it without dealing with the axle/wheel interface. Many of these saws come with the wheels no co-planer on purpose. It sets up a level of tension that makes tracking more stable and reacts more slowly to upper wheel adjustment. Sometimes making them co-planer helps a person get a particular saw tracking properly but it (usually) makes it more finicky as well. This isn't to say some used ones (and maybe the rare new one) isn't too far out but with the used one if nothing is worn it is likely due to someone fiddling with the lower wheel when they shouldn't have. Messing with the lower wheel should be a last resort, and even then it is usually best to start over from the beginning instead of going there. Once that factory setting is gone it is likely never coming back.
I see the co-planer issue a lot like bandsaw guides (I will address them in a moment) when one changes the planer alignment of the wheels it forces them to do a comprehensive top to bottom adjustment/tune and I am convinced far more often than not the eureka moment attributed to the planer adjustment was really do to the care taken in retuning the bandsaw. Guides are similar. You often see people who change their guides from stock blocks or bearing guides on a $500 saw to a set of $180-$230 Carter guides and proclaim it is a whole new saw. Part of it is confirmation bias but I think a lot of it is again the careful top to bottom tuneup. There are reasons to change guides (I am not quite bored enough to go into the whole scope of guides) but there is no night and day difference between the functioning of a simple metal block guide and a set of Carter guides, in fact, the block guide is actually a better guide in many ways. However, that is a subject for a different day.
Of all the laws Brandolini's may be the most universally true.
Deep thought for the day:
Your bandsaw weighs more when you leave the spring compressed instead of relieving the tension.