I would think any of the replacement bushings are good for life. The original bushings are some kind of rubber or plastic that liquified with age, or perhaps from exposure to the screw lubricant. The old bushings just disappeared into a butyl-like goo that takes a long time remove. I started removing the bulk of the residue with a screwdriver blade, then softened the remainder with gasoline and wiped it out with paper towels, then used carb cleaner spray to remove the last traces.
I studied all the DIYs and videos, and would just add a couple of tips:
1. Run the seat back to access the front nuts, then forward to expose the rear bolts, then run the seat back to put it over its rails so they don't stick out.
2. Tilt seat inward and use a 2x4 block between the seat and the sill to hold it up while unplugging the connectors. After this point, do not use the car's key. Those who do use the key, are those who forgot to run their seat back, so they do that and trigger their airbag light.
3. Seat is heavy, get a helper to lift it out and in. Failure to get a helper allowed my sharp seat rail to cut through two towels and scratch the rocker panel going back in.
4. As soon as screws are out, use a nail or pencil point to count the threads showing on each screw and write it down. Should be the same on both, depends on where you stopped the seat going back, mine were 20.
5. When screwing the new bushing holder back on the screw, count the threads again to put it back where it was.
6. When replacing each re-bushed screw, insert the flexible drive rod into it and then insert the end of the screw into its guide hole inside the rail, which will then direct the drive rod into the motor at the bottom. If the screw won't hold the end of the flexible drive rod, put a little tab of duct tape on the end of the rod and jam the rod into the screw's hole.
7. Note that the guide hole has a plastic insert that can come loose. Must use the insert because it centers and acts like a bearing for the end of the screw. If the end of the screw won't go into the plastic insert, tap it in.