Think of MIDI files as a kind of sketch.
Sometimes you have a good melody in your head but just don’t have the right sound …. that slows you down.
In MIDI format, on the other hand, you can treat the growing composition like a sketch.
A neutral piano preset is a good place to start in order to get a good focus on chords, melody, etc. Later you can try out the effect of different sounds, octaves, see what works for the song and finally bring everything together.
This approach can be a game changer in terms of efficiency, especially with orchestral themes.