If you don't know already, you could use MuseScore - then write up the notes, then output midi and squirt the midi file into LMMS or any DAW. Takes hardly any extra time, and of course you can input the notes in directly if you have a Midi keyboard or Midi controller to introduce expressions.
The extra time to do the MuseScore step is pretty minimal, and could save time overall.
MuseScore is free, and it's quite easy to write music - you can convert to PianoRoll format easily if you want, but you can also put dynamics in.
For scales it's easy - just write the scales or arpeggios you want. They can be transposed easily too - though obviously this can also be done in a PianoRoll. Some things are a bit harder, such as reversing an arpeggio - that might require a more expensive software system, such as Sibelius, Fanfare or Dorico. However, it should be possible to do some things by switching back and forth between a notation software system and a DAW such as LMMS.
Simple example - reverse a string of arpeggios. [not so easy in Musescore]
Output to midi, import to DAW e.g. LMMS. Reverse the PianoRoll pattern in LMMS and output the midi again.
Input back to Musescore and the arpeggios should be reversed. [I must try this - I'm sure it should work]
Could also invert themes - in a similar way.
The final decision as to whether to work in a notation system or in piano roll can be left to the artist, but there's merit in both approaches.
Anyway, this might help some people. Not everything has to be in 2 or 4 bar loops, or in 4/4.