Yes... I used this trick all the time. I generally play with at the very least 20 thanes.
The thing is, it doesn't seem to make all that much difference. I think the game should just let you recruit however much thanes you want, without adjusting to your actual numbers. Let's say around 8 per recruitment. Anyway, if the clan can afford it, there's nothing wrong with having more thanes -- it doesn't seem to give that much of an advantage anyway.
>
> One thing I was just reminded of was a gamesmanship trick for getting a
> lot of weaponthanes.
>
> As I recall it, how many weaponthanes was you could recruit was restricted
> by how many you already had, because people resisted getting the clan
> ratios out of balance.
>
> But I found that if you sent most of you weaponthanes off on a mission,
> you could then recruit a bunch of new ones, and then when the mission came
> back you'd have a huge number of weaponthanes.
>