Having rebuilt myself or supervised the rebuilding of hundreds of engines, I have never heard of reringing after two hours. It does not matter if it is a Briggs model A or Wisconsin VG4D, if done properly there is no reason to tear it down again. This does mean that you must wash your block after boring, glaze honing and lapping. Block must pass the Kleenex test before reassembly starts. Rubbing every part of the block with an oil dampened Kleenex will tell you if you missed anything. ANY evidence of dirt means rewash. This also teaches you the patience to take your time and do it right. Only time I've had to rebuild the same engine twice was an engine that came back 6 years later, it was a Kohler 341 used on a cement mixer. Doubt it was anything I did wrong or left behind. Motto to my students: "If you don't have time to do it right, you'll have to make time to do it over"