You are correct, sir.
Generally, it's

to settle on top of a food tile like wheat or bananas, as food is king in this game and you won't get nearly the yield from it as you would by farming it. Sugar, deer, and spices don't provide as much food, but I would still recommend plantations over settling on top of them if at all possible. Ditto (usually) for high commerce tiles like gems, gold, silver, and dye.
High production tiles (copper, iron, horses) are more of a judgment call: once again, you won't get the yields by improving the tile, but you make the resource pretty much pillage-proof. I prefer to work the tile myself and take my chances with barbs and AI enemies, as fighting them provides valuable XPs.
The more mediocre resource tiles are very commonly settled upon (ivory, wine, silk, furs, etc.). You're not missing much by forgoing their yields, and you ensure that as soon as you have the necessary tech, you have instant access to the resource.