Don't know if all spas are the same (doubtful), but my spa has jets on all four sides, and presumably potential leaks at all jet sites, and other plumbing junctions, so I'd consider at least the possibility that a tech could need to access any side panel.
I remember seeing posted at least a couple times that most servicing is done in the equipment bay.
Maybe some tech's could comment on how often they have to access other areas of the spa.