The truss rod adjustment affects neck relief, which is a measure of the amount of bow in the neck. It is not used to adjust action height, although an adjustment of the truss rod will affect action height. Once the bass has been set up, certain things are not normally going to change by themselves. The saddles should not move, the angle of the neck where it is set into the body is not going to change, the string tension is not going to change. But when the strings start buzzing with a change in humidity, something certainly has changed. The neck has bowed back, reducing the relief and also the action height. Since the only thing that has changed is the neck bow, adjusting the truss rod should be all that is needed to restore the bass to exactly where it was. Again, the truss rod is not an action adjustment. However, if the only thing that has changed is the neck bow, then the action height is a very good indicator of the amount of relief. If you know what the action height was before the neck changed, you can set it back there very accurately by looking at the action height. This might be the best reason for using a 1/64th scale for measuring the string height. After the bass is set up and you have an action you like, measure the action height. Whenever you notice a difference due to seasonal changes, adjust the truss rod to restore the action height. Don't worry about relief measurements if the relief was already set correctly originally. If you prefer setting action by feel instead of measurement, then the procedure is still the same; adjust the truss rod for the same original setup feel, instead of the same measurement. Not as precise, but should still get things close. If you prefer very low action and a dead straight neck, you should also be able to get close by adjusting the truss rod to restore the action height. But a dead straight neck is critical; good to check actual neck relief also in that case. And when the action does change with the weather, don't simply adjust the saddles! for all the reasons above. The saddles haven't moved; the neck did. You need to restore the relief.