I'll change strings as soon as they sound dead to my ears. Of course, treble strings last longer, but what should I do with all the remaining trebles - go fishing?
When the basses are done, I'll usually change the trebles as well.
Momentarily, I've strung up »Harley Benton Superior Classic Coated HT«. I'm sure it's an OEM of »RC strings professional RC-10« (which I bought at the same time, so I could compare directly). Basses stay brilliant for quite a long time, but they tend to show fret marks pretty quick on D and A. I move the basses 1 cm after 10-15 playing hours and will try to do it a second time, if the sound is still o.k.
I always start winding at the roller, fixing the string like shown on the picture. 2 or 3 windings give enough headroom to move the string by 1 inch or so. The string won't slip out of the roller, even when unwinding it completely.