AS-SETs can get rather silly, I made a logarithmic graph showing the size of all AS-SETs when fully recursed in different ASNs. The top 500 are unworkably large to actually use.

The top offender is AS39533:AS-PEERS (at 98484 ASNs), or but things like AS-DECIX are close by "Only" 100 or so ASNs.

I can't really see how generating these is at all worth while, Given that right now there are 82684 ASNs (according to bgp.tools) in the table. I can't see how generating things that are bigger than the internet itself is useful. Most of the AS-SETs that are above 10,000 ASNs are IXP route servers, meaning the only real valid strategy to filtering IX route servers is to perform ROA validation, and basic prefix size/validity policy checks.

If you are interested, the full list is here https://docs.google.com/spreadsheets/d/1IP69v5saBXGimpvgJL76UAzxHj-jhQ3Bh4xDRt-1Nlo/edit?usp=sharing