I guess it all depends on what you do. We change oil every 15,000 miles which means about 3 or 4 oil changes a week so they see a lot of use. Zoro had another 20% off promotion and I was going to buy another pair, but I couldn't them in their catalog. I did however buy another pair of tall jack stands at 20% off.

http://www.zoro.com/i/G3036476/

I have a pair of tall Lincoln jack stands which are awkward to move around.

http://www.jackxchange.com/products/W93525.cfm

The OTC with the round base roll. We routinely lift the entire rear of a truck and put the frame on jack stands to grease the brakes and check the rears.