Pretty much yes. With some mods, I would say they do seem to allow more current through and therefore seem to run a bit hotter than others. For example I have a Mako, which is an entirely mechanical mod, and when the bottom button is pressed, the battery directly contacts the body of the mod, and the atty connector. This means in other words there are no wires, switches, springs or solder joins involved in the circuit. I found this mod clearly ran hotter with the same battery voltage and atty than say, an Indulgence which uses a conventional switch.
Other design factors could of course impact on the performance of the mod, for example the airflow allowed by the atty connector.