On ours, the automatic feature finds level for you. It is not set in one position by length of the jacks, it is set in the coach level position, regardless of how long each jack extends. It is often easier to use than manual but on some sites, manual seems to work better. We have Power Gear Jacks.
When the auto feature is having problems finding level on a particularly lumpy site, we can often solve the problem by putting wooden blocks under the jacks on the lowest side (either front, back, left, or right).