longest repair I had ever done was about 5 hours with my teen when we bought the teenager civic car. That was timing chain, water pump, engine mounts, spark plugs, oil, and coolant.

This repair ended up taking me about 29 hours. I had to take off A LOT of stuff to do it without dropping the engine. Parts and new tools were about $1250 (I had to buy a nicer $250 code reader to be able to initiate the relearn on the timing and mass airflow, and I do the water pump, spark plugs, and thermostat while in there.). If I had to do it again, I think I could probably do it in about 12 hours.

In grad school I started doing all our repairs out of necessity. Now it may not be a complete necessity, but still think it saves a ton of money and I teach my kids to not be afraid to work on their cars.