My Jiuta teacher once warn me my shamisen joint might become loose if I take apart regularly.
But from what I read many professional travel with their shamisen separated.
What your opinion?
Hi Louis,
That makes sense to me. I imagine frequently dismantling/assembling the shamisen can wear down the wood in the joints (as the wood of the joints rubs together every time). Of course, I suspect this becomes a problem many years down the line, depending on how frequently they take it apart (once a week, once a day, etc).
If/when it does wear down, a thin shim can be glued on to the tenon, so the joints fit tightly again.
Also, the joints can become loose depending on the weather. On humid days, I notice the joints of my sao fit tighter, and are looser on drier days (as the wood shrinks)
Just my two cents. 
Professionals probably don’t have much choice either - they’ll go where the money is, and separating the sao is handy for travel, it’s what a mitsuori is supposed to do. And they might know a few additional tricks what to do when the joints have become worn and are getting a bit loose.
Also, they might use the option of dumping their instrument on the 2nd hand market when they’ve used it for a while.
Just an educated guess - I think it’s maybe one of those “don’t try this at home” things 
My koto teacher(of course also play jiuta shamisen) said he takes shamisen apart because he don’t want everyone thinking he was a shamisen player.
My koto teacher(of course also play jiuta shamisen) said he takes shamisen apart because he don’t want everyone thinking he was a shamisen player.
lol