The plastic cutting boards work well, but I prefer 12mm BB ply--don't like the plastic sticking to my blades.. I generally cut to width on the table saw, then round it with the band saw, also use the BS to cut the slot for the riving knife. Could use the router with a trim bit using the original insert as a template, but I'm happy with the band saw results for now.
For dado stacks used for rabbets, I just stack the blades and cutters without shims, so it's always the same size. For rabbets, you are burying the blade in a temporary fence anyhow, You expose only the amount needed to cut the rabbet. So for that purpose I can use the same insert for a long time.
Never thought to put a finish nail in as a hold down. Thanks for that, although my inserts never lift out. I could just glue on a small tab to do the same thing, since the opening for the riving knife cuts all the way to the rear edge of the insert. Two tabs would keep one from flexing lower than the other.
I usually use a 2x over the blank insert to really hold it down. I often just use a little tape to level because the depth of the insert opening is very close to the 12 mm thickness of BB.
The more I do, the less I accomplish.