Actually got rotate but one time only, when fit new to the rear you rotate the rear to the front mah!..haha
Cost effective or not, both have pros and cons. Most rotate because front wear shoulder and rear wear center. As I told bro. SF if front and rear wear is good why pay for rotation. Most shop charge even to rotate, then if balancing out, you need to balance and quite many I know do alignment also. Like most say last 50k km, means at least rotate 4 times. 2 tyre change you already save 4 times rotation and balancing RM.
Cost of changing tyre is not cheaper, but paying extra like rotation cost more. Change two at a time is cheaper but got to pay twice so is the same cost.
Did mention many times already the pros and cons.
It is more to the safety aspect for me.
4 tyre change you rotate until all 4 tyres bald. Period when 4 tyres bald, is danger period. If change 2 at a time, at any time you will still have two tyres with thread pattern....
---------- Post added at 04:15 PM ---------- 6 hour anti-bump limit - Previous post was at 04:13 PM ----------
If both sides wear inside, or both side wear outside, like bro. ixeo mention, remove tyre, re-mount them, then cross left to right, so the direction still points forward...