Is there a convention for type of switch used and where?
I can't give you a 100% correct answer, but I'll try as best as I can, having some experience with much smaller aircraft (even than the TBM850):

As far as I know, there are no strict conventions for this and this is why you see most aircraft types equipped with their own panels and cockpit design.

You always have to keep in mind that aircraft manufacturers put most of their engineering efforts into designing aircraft concepts for a specific market and then casting their ideas into an actual airframe that fits all the systems that are needed to operate the aircraft.

Allmost everything else (engines, landing gear, avionics, A/C, lights, APU, steering, braking and anti-skid systems etc.) is developed and manufactured by external suppliers with the aircraft manufacturer responsible for adapting and orchestrating all the systems.

This might lead to the aircraft manufacturer simply using already available switch assemblies or only slightly modifying the suppliers' reference designs for panels in the actual aircraft.

IMHO, this is easily recognizable when looking at the cockpits of (especially older) aircraft where there was no concept of the cockpit as a whole. Whatever switch assembly was needed was just somehow installed into the panels.

As Boeing's 707 was a great success, its cockpit design (at least partly) found its way into the 707s successors/derivates/siblings 727 and 737. This lead to the 707 setting the cockpit design paradigms for following (Boeing) aircraft.

Also, from a pilot's point of view, there are some semantic aspects about choosing a switch that 'feels right'. For example:


push-buttons to start an automated process
korry-type switches for switching automatic systems on or off or for on-off switches that might be controlled automatically (And therefor show their status; Airbus uses these a lot due to their cockpit philosophy)
toggle switches for everything that needs an on-off type switch on low-level without other systems needing access to it (for critical switches with safety cap as seen in the 737 overhead panel)
rotary switches for mode selectors
potentiometers for everything that is finely controlled by the pilot
rockers maybe for mode selection between two modes where neither of both is just "off"


are very intuitive to me. This might be training or just experiences from everyday life, but I understand what they are doing even before having read the manuals thoroughly, which makes it easier to remember which switch does what.