And what happens when a large clan captures a fief from small one? with a large number of buildings? ))
1. greate sub clan,
2. build up
3. grab well-fortified fief by main clan
As soon as you split off the sub-clan, you've just reduced the number of structures your main clan can have. If you have 50 people available, it doesn't matter if you have 50 people in 1 clan or 5 people in 10 clans -- you have access to the same number of structures either way.
The problem with chadz idea of basing it on "number of players in a fief" is that smaller clans have a higher overhead cost of "people who need to leave the fief". If my clan has 10 members and yours has 50 members and we both operate 1 caravan runner then I've lost 10% of my structures and you've only lost 2% of yours. If we both additionally operate 2 raiders and 1 army then I've now lost 40% of my structures and you've lost 8% of yours.
Basing it on the "number of players in a clan" rather than "number of players in a fief" would help keep the relatively higher overheads of small clans from being as detrimental to them.
Although I still like the idea of basing it on the number of troops present. If you are paying for 2000 troops to sit in some fief, why do you need "heroes" to sit there with them and maintain walls?
Yet another idea is to use this new "tick" system for crafting. Each wall costs 1 tick per day or whatever, taken round-robin from each clan member. So a clan with 10 active members and 200 inactive will be no better than a clan with 10 active members, period.