You asked how often they should be imbalanced?
It's a good idea to have them balanced when they are rotated, around every other oil change.
2001 WJ 60th anniversary edition 4.7 quadra-drive
5" hybrid lift, 265/70/17 Guard Dogs load E, bilsteins 5100's, addco sway bars, JKS front quick disco's, JKS adjustable track bar, KOR durometer track bar bushings, IRO crucial path front L.A.s, 1.25" Spidertrax spacers
Colorado Jeep Club Member #262