It may vary nationally, but around me they usually sell 8 footers as well as 88" (7'4") studs.
If you use an 8 footer to frame a wall, once you add the top and bottom plate of the framing, you're over 8', thus the 8' drywall won't cover it up . . . that's why they make the 'shorter' ones . . . and why if you redo drywall in your own home, there's a good chance you'll need to cut 4" or so off every sheet of drywall you hang on the wall vertically.
Lowes and HD here sell two lengths predominately. 92 5/8", and 96".
The 92 5/8" are for 8' ceilings. That length, plus a bottom plate and two top plates gives you about 97". Hang a 1/2" sheet of drywall on the ceiling and you've got 96 1/2" of vertical wall left. After accounting for any inconsistencies in construction and out-of-level situations you end up with 1/4" to 1/2" of space left between the floor and the bottom of the drywall you've hung on the wall.
Here in No. CA, both Lowes and HD also sell 114 5/8 for 10 ft walls as well as the studs for 8ft walls. When I built my shop (with 10ft walls), I ended up buying the full 10 footers because they were priced cheaper than the shorter studs (go figure). I spent some time making camp fire starter on the chop saw before I started framing. It always hits me after I do something like this that my time may not really be free - Live & Learn has always been hard for me.