A physical button and a button in groov View are very different and need to be treated differently.
When it comes to physical buttons (in PAC or EPIC), use the built in latch function.
So your chart would look for an on-latch event.
Once it has read the on-latch, it can clear it ready for the next button press.
This way, the operator does not have to hold the button and your software can just read the on-latch when it needs to check the button.
You can also use the get-and-clear latch events to both read and reset the latch from your flow chart.
When it comes to groov buttons (which you seem to mention in the last part of this post - if I am reading it correctly), then you usually have a UI chart, a chart that just takes care of the user interface and it has a pretty good scan rate (say 100 msec).
groov View writes button events straight away, so there is very little delay in sending the button press from groov to the strategy. There is the usual 1 second scan rate for reading variables, but not in writing them.
So, best practice is to use latches for physical buttons and use a user interface chart that handles the groov View button presses.
@philip said it better in less words!