Strictly personal opinion here, but my preference is to mount everything and check by firing tall target test. Not only will you pick up tracking information, but you can also double check the alignment of reticle to bore (although I guess that's a hot-button issue to some).
If you have the interest, do BOTH. Check the scope on its own in a mount, then slap it on the rifle and fire because sometimes weird things happen that aren't always the scope's fault: odd ring torque, mount misalignment, etc. Nothing beats real info.