The real reason I do so is as follows:
TRA procedure (as I have experienced myself sometimes in cases like this):
Flight-route EHAM-DTTJ via DTNH and therafter back to EHAM departs from EHAM as TRA153;
First stop is DTNH; passengers for DTNH going out, passengers at DTNH for EHAM goes in;
At DTNH the flightid changes in TRA154;
Next stop DTTJ; Passengers for DTTJ going out (in some cases the pax for EHAM as well), there after all pax for EHAM are going in and the flight depart as TRA154 from DTNH to EHAM. (AND GOES NOT TO DTTJ AGAIN TO PICKUP PAX FOR EHAM)
Additional benefit is also that spotters between DTNH and DTTJ allways have the correct route-information about this a/c all the time, regardless of the flightid that it performs
So this is why:
TRA153 EHAM-DTTJ via DTNH
and
TRA154 DTNH-EHAM via DTTJ
Hope it is clear why I do so and if you do not agree with this view feel free to put it in the d/b as you like.
Kind regards and have a nice Sunday!
John