What age is the truck? The newer tachos can record more effectively I think if it’s fitted after 2012 is when the latest software update was.
To summarise though…
OLD: ANY minute with ANY driving is counted as a full minute if driving. It will also round up the minute before and the minute after (the sandwich effect) which is where your time creeps along.
NEW: ANY minute where driving is the longest activity will be counted as driving so if you drive for 29 seconds but are stationary for 31 seconds as other work it will count as a minute of other work.