Coincidentally, I haven't used my Symmar APO 210 in several years, but took it out this weekend for a photo I needed it for on 5X7. Abandoned church with an interesting horizontal sign on the top front of a porch. On the top of the building maybe 25' back, a crooked white cross. I focused on the sign, which was fairly close to the camera. The cross was out of focus. A little tilt brought the cross almost into focus. Just to be sure closed down to between f:32 and 45. Negative is plenty sharp enough for any size print I can make. I'd have never given it another thought but for this thread. Probably by focusing appropriately between near and far I could probably have gotten away with one more stop open. But this was less trouble.

Is this the sharpest aperture for this lens? No. But it doesn't make any practical difference with my real world parameters. If you're shooting for 10' tall murals, that's another story. 16X20 is currently my maximum print size and that is not pushing a 5X7 negative very hard.