Yes I completely understand. If you add 3" lift and lower them 3" your putting your bump stops back where they will function no madder the compressed length of the shock. If you go any further you will just ruin your up travel. Why dont you just take it off and measure if you dont believe me. Different year LC shocks can have different lengths also.
There may be some more truth to this when we're talking about the axle compressing at an angle (flex) vs the axle just going straight up and down. But at the end of the day, extending the bumpstops by the amount of lift is not the correct way to do it.