From what I read..every 10-15k km

Well the point is you dont wait until you can visibly see the tyre makan sebelah then only change.

Your SC lazy, or he see you dont want to pay, and dun wan argue with you.

Basically rotate, balancing and alignment during EVERY OIL CHANGE for max tyre longevity.

Whether you have the budget for it or not,
or is it worth it or not for your particular car vs your driving style, is a different matter =D

For once I totally concur with the SC and have been practsing so for  umpteen decades .
Generally, all my tyres stay in the same 'corner' from new to end of life (of say 115k km) .........
on several different cars till todate .

Edit:Yes, end of life of 115k km for an XM2 at the same corner 'untouched' till its 'end' .
So much on extended tyre life for 'regular periodic tyre rotations' which sounds like a myth to me .