For 8x10 prints that I usually do, going full open doesn't seem to make the final image any softer. I use 6 element EL-Nikkor.

Typically, I do whatever it takes to keep the exposure time reasonable. Make it too short, dodging/burning accurately becomes an issue. Make it too long, my arm gets tired.

One thing I ran into is that using whatever the formula/system gets the exposure close, but if the image size is changing as much as double in area, our perception of the images change. I often have to make significant changes to make them "look right". That involved as much as 20 to 30% change in exposure and half a grade in contrast.