Actually depends on what remote control and what button.

Some remote controls will continue to send infinitely (or until end of battery) for some functions, line volume up/down, while they will send for a limited time for other buttons like "input tape" or "channel 3".

Some remote controls will continue to send while the button is pressed, but will after a limited time deactivate itself under the assumption that a button is stuck (such as if you have put something heavy on the remote).

Some controls don't make use of any repetition at all. One button press (any button) results in a fixed-length burst.

Play with your remotes. Press a button with your hand blocking the transmission. Remove your hand and see if the receiver still responds. Repeat for different buttons and try different delay time before removing the hand. Or build a simple IR detector that lights a normal LED so you can view when a transmission is active. Some older digital cameras could also see the IR directly, allowing you to see the light directly on the camera display. More modern cameras can normally only see high-power IR diodes in darknes - there is a IR-blocking filter before the image sensor that greatly dampens the IR sensitivity.