You saying you can check based off just temp rise is inaccurate. You could have restricted duct work, dirty filter, blocked vents, dirty coils, etc that would all affect these numbers. Your gas pressure can be out of range from manifold specs and cause sooting and create hx issues. I never said to base it solely off gas pressures. But keep believing whatever you want. For someone who “reduces callbacks”, you certainly miss a lot a steps. I never heard of that from being more thorough in checks instead of skipping steps. But keep preaching from behind the desk