Five, six, seven, eight stations can be put to use, but with respect to progressive loading, four stations are definitely better than one. I also value the inclusion of a powder cop or lock-out die. I won't dismiss the importance of that, though others would. I would only exclude it where the charge fills the case and a double-charge would overflow -- which is pretty common for magnum handgun and intermediate rifle cartridges.
So rather than excluding a powder-checker station, I would suggest that depriming is best done prior to case cleaning. Otherwise, you're loading a dirty primer pocket. Some don't care, but I won't dismiss the concerns of those who take care to prepare their brass thoroughly anymore than I would dismiss those who use a powder-checker.
Because I find resizing to be the operation that requires the greatest force, I do it while depriming. That allows me to load fully prepared brass and the loading process goes more smoothly.
Also, while I personally favor the Factory Crimp die for roll crimp cartridges used in revolvers, for the handgun cartridges that headspace on the case mouth like 9mm, .40S&W, .45ACP, the FCD is not compelling.Properly adjusted resizing and bullet seating dies will full-length resize and taper crimp the cartridge and the factory crimp die is unnecessary.
Finally, with bottleneck rifle brass, I only use two stations at most. I decap and neck only resize with a type-S bushing die with no expander ball and use a slight amount of case lube on the outside of the neck, but I still clean the cases afterward so that both the primer pocket is cleaned and also the case lube off the neck.
Also, if the rifle brass needs to be trimmed, it will be after resizing. I don't trim on the press, so it has to come off anyway. So when I reload bottleneck rifle cases, it's just powder and bullet seat. I don't crimp more than the minimum neck tension provided by the correct bushing size.
Because of things like this, one of the best values of a progressive press is the case feeder because even if you're only doing one operation, it's still much faster than a single stage press or turret without a feeder. And if you're doing two stations with a case feeder, that's an economy of motion that still beats a turret.
So while some may make use of 5 or even 8 stations, even two or three would be an improvement over the alternatives.