Depends on how long you lose
oil pressure and how stiff the valve springs are.
I have seen several aluminum rockers without bearings/bushings that have galled so badly that they are practically "welded" to the shaft and couldn't be beat off with a hammer. (the usually break too when they seize). I have seen even more so worn out that the I.D. is visually egg shaped.
The next post will be from someone who has run rockers without bushings or bearings for a decade without a single problem. I don't doubt it, especially with a flat tappet cam. I'm just reporting what I found when I was researching FE rockers for the Erson design.