100 hours feels like the correct time to; facilitate the full cleaning and lubrication qualities of a good diesel grade oil and utilize the cleaning properties of the oil circulating system and filter.

If you change at 50 hour intervals, you; throw away good oil and if you change the filter, a half used filter. Both of these are a waste of money(as well as a 50% additional waste issue).

I read someone with a fuel polisher system say how clean their engines fuel filters were as they regularly change their polishers filters. In that case, that sounds like overbuilding to me.