I can't imagine trying to level cabinets with shims... This is my second home kitchen I have done with EZ Levels. I did have to add a 1x4 into the toe kick area to space the leveler out from a wood support block stapled right where I wanted to place the leveler. The EZ Level site has a specific video to show you how to get around this any other obstacle with installation. I also followed the general cabinet installation videos which are extremely helpful for a DIY cabinet installer. I had to cut my floating floor after it was laid to place my cabinets securely on the sub floor. Because of this I had my cabinets pressed firm against the wall when leveling which I think led to some struggles, definitely move your cabinets away from the wall 1" or so to allow the rear to rock as needed. I found my island very easy and quick to level compared to standard cabinets on the wall. Warning: Do not loosen the levelers too much, even if the rear of the cabinet is not coming down! You will unscrew the threaded rod and have fun getting it reengaged.