No, it's not. I don't know what he ideal grilled cheese is, but you can get many, much better, grilled cheeses by not using the first two of those items. Lots of butter is spot on, though.
As someone who cooks grilled cheese sandwiches for a family twice a week, and likes to experiment, I can tell you that cheddar or gruyere, mass-produced white bread, and lots of mayonnaise, is preferred by some.
And someone else will chime in with something else. I don't know what the 'ideal' grilled cheese sandwich is, but I'm willing to wager a lot of people think it isn't made with American cheese.
Never tried that. My ideal is bechamel sauce with cheese on top - shredded for the added surface area when browning. This is based on a typical croque monsieur recipe. It's very easy to make bechamel in about 10 minutes and it keeps for a week or more in the fridge without issues.
butter 2 slices of whitebread, place cheddar cheese (doesn't matter the type.. nothing aged) and pan fry. It's just enough to toast the bread and melt the cheese. American cheese will have a weird flavor.
You savage. You slice your own Velveeta for grilled cheese. In fact, I think that sounds good right now.