Depending on the clock you are working on determines the quality of the bushing job you do. Early American clocks were mostly thin stamped brass plates with the pivot holes stamped to almost look like a bushing. This probably hardened the brass a little more, provided an oil sink, and gave the pivot hole a little extra life.
For a clock like this, the hole can be opened up with a special reamer which only cuts on one side until the hole is brought back to center. Then a bushing of the proper height to match the plate, is pressed into the opening. It is then opened up a bit with a broach so it's just slightly larger than the pivot. Too tight and the gear will bind up.
It's important to match the thicknesss of the plate. Some repairers sometimes leave the bushings too long thinking the added surface will take longer to wear out, but it's not the case. A long bushing like this pic causes tunneling, which is wear, but not all the way to the end cause it can't reach, but after it tunnels it reduces the end play of the gear which is no good.
On the eveyday, plain vanilla, American clock movement, a visible bushing isn't an issue. Same for a modern cuckoo clock. ( I know, you're probably wondering why anybody would even waste a bushing on a cuckoo, but sometimes you have to.) On finer French clocks, which rarely need bushings anyway, or significant tall case or banjos, you might want to make the bushings as invisible as possible. This can also be done with special cutters.