I wipe the bass as I change each string. Do any of you take off all the strings at once? That's something I was told not to do by a luthier. I guess his thinking was that if the truss rod is exerting force to counteract the strings and then you remove all the strings, it is putting unnecessary reverse pressure on the neck. Of course, modern necks that are five piece or have graphite may not even require much truss rod adjustment. It's kind of old information that may have applied more to how necks used to be made - still it's a habit for me.
I've done it before. If you want to thoroughly clean the fretboard, it's kind of necessary. But if you're the kind of person that replaces their bass strings more than say, twice a year, the "change the strings one at a time" method is definitely better for the neck. So my thought is, if you're just changing the strings, do it one at a time, if you're cleaning the fretboard also, take them all off, clean, then put the strings on.