It was purely a random selection designed to be different from the standard apportionment of an hour.

Not offended at all I think I simply failed to elaborate as to the fundamental purpose of the approach.

In retrospect it would probably have made more sense to have picked a really odd subset - say front loaded like:

{0,1,6,11,16,21,26,31,36,41,46}

such that clear 46 min and above is treated as an hour and sub sets of the remaining 45 mins are apportioned accordingly (ie 21-25 mins treated as 0.5)

Obviously the above is a fairly big shift away from the OP so it would have just added yet more confusion