Raceways of different trade sizes connected together

[dashburn]

Is it allowed by NEC to connect different trade size raceways using a reducing fitting in the middle of a run? Example; 50' run of 1" RGS connected to 50' of 3/4" RGS using a reducing fitting in lieu of a box or condulet.

 

[tom baker]

Yes, if conductor fill is sized for smallest raceway
But:
Makes pulling hard as you will hang up.
The next person will say, hey we have a 1" conduit here, lets go with more wires.