It's ugly, and inelegant, and it works
It's what I'd do too. The only other way I can think of is to write a Visual Basic Macro that programatically scans through the logbook and does the calculations, and is called with one elegant statement =flighttime(30) etc. Lots more effort to come up with the same number.
I'd say do what Keef says and hide the inelegant columns
RC