Yes, keep the spare..........it also allows you to fully rotate all the wheels around the car thereby get the best out of all 5.
Assuming you do not have five directional tyres ! For some reason the previous owner of my car fitted Toyo Proxes T1-R’s which are dedicated "left" or "right" (uni-directional). The spare is omni-directional, so is fine for that purpose, but not to truly rotate them around. When I next buy tyres, omni-directional is what I'll be going for, so that I can indeed rotate them.
