Ok so I couldn't stop thinking about this and needed to jot it down.
I kinda changed opinion but not stance. I don't think there's a correct answer. Having accesible (relatively) simple sieges vs week long ones isn't wrong vs right as much as it's catering to different aspects of the game. Like it or not both ways ruin the game for different people.
I still advocate for finding a different solution than just going back to 24h sieges permanently. So what about variable siege times? It could be every other server siege is slow and every other it's fast so it changes with new world(bad idea). Or the siege time could change with the server life so that siege times either increase or decrease from a base value to a min/max over the course of a few months (better idea). Or what about changing the siege times based on the season? (best idea) This could be larp friendly if winter has the longest siege time and summer the shortest (though maybe for balance reasons either autumn and spring should have short siege times and summer long), different seasons would be safer for base building and rebuilding which would be dynamic and fun.
Or maybe it's possible to make siegeing something to prepare while not spanning 5 days. Lets say you can make a siege challange/declaration(somehow) which will take 3 days to allow the siege, you make the challange against a claim and then you can build and use siege engines near that claim only after 3 days but use them almost instantly. The owners of the claim are warned about the challange by a buff or something. This would provide a specific time when the siege will happen, it would allow for planning from all sides but the actual siege when players try to outsmart eachother would still be confined to a reasonable time period.
Please, bust my ideas.