I am into my annual this month. I have set up my engine so that it takes about 1 hour to remove and same to put it back on. I have removed it for 2 of my 3 annuals so far. I generally ask myself why I am doing this as I am removing it, but once I get it off, I feel much better about it, because I can get a really good look at everything on the back of the engine, thus a thorough inspection.
For some of you that saw my plane with the engine in place, here is what the firewall looks like without the engine.
