Brown bear,
If the guys who are tied down by spending a lot of time travelling are paid more than £100k Pa, and if they spend more than 30% of their time travelling it becomes simple maths to make any sort of move, however you really will need to know where they are travelling to and from because location and time are always dependant entirely on the weather situation, and in the Uk we don't really have two days that are the same, rough weather will stop most helicopters, that also has to be part of the thought process on costs, for once stopped and weathered in your calculations will go to Rat Sh** very quickly.
Peter R-B
Vfr