How to monitor a switch's state and do X if switch has remained in state B

[Arrch]

switch_timestamp = millis() + ( 6000 );

What this means (assuming timestamp isn't changed), is that after 6 seconds, the timestamp will will be equal to the current time, so that means overall, it will run again 6 + interval seconds. If you want it to run every minute, then you simply need to add 1 minute to what the current timestamp is:

switch_timestamp += 60000;