First of all: I'm using the CubeIDE toolchain offered by STM.
Some of the STM32 microcontrollers have multiple ADCs (for example STM32F446xx) and offer a multi-regular-simultanuous mode (DualMode or even TripleMode), where the ADC1 is set as a master and triggers the other ADCs, which are in slave configuration.
When I use this configuration in the CubeIDE I can still set the trigger for the ADC1 to a timer, and not use it in continuous mode. Does this configuration make any sense? I could also just set the trigger for all the ADCs I want to be synchronized on the same timer, no? So the way I understand it, multimode only makes sense, when I want to have it running in continuous conversion mode and have all the ADCs be synchronized.