Repeatability is an issue.
And the ability to accurately set cuts consistently is probably not going to be a stong point on the Rigid planer with the ruler and pointer style gauge it probably has. First and foremost is to plane parts that absolutely must match at the same time, say cabinet framing for example. As far as getting the right thickness you will learn not to take too much off with practice. I hadn't used a planer for a while and just got a new one set up. I did the same darn thing. Ok so you lose, chip or miscalculate and need to add one more piece of 1X2 to your pile of sticks that will become cabinet door frames. You can sneak up on it and get it right with the aquired skills I mentioned above. It's not that it's so hard to match the thickness as it is time consuming. You'll find yourself planning your planing sessions to do all of one thickness for a project at once, not as you go along. The most essential ingredient it a decent caliper to measure with, digital or good old direct read. Just a few thoughts, hope it helps. You will love having the ability to thickness your stock.
Larry