As a songwriter I often write songs that uses more than one motif. Without the change to the other motif the song would either be too short or sink into boredom.
Most theories I have read were about chord progressions and melodies, using dominant chords and leading notes, and so on, but I was missing material on the time part of the puzzle.
Therefore I am looking for theory on the proportions of musical motifs and sections, and about popular music in particular. (Popular in the sense of non-classical, including all music based around verses and choruses, sung and played).
I have a gut feeling that the number of bars needed to tonically and rhythmically build up a change can relate to the number of bars before the change, but maybe I am off the track. Too less and the change would feel like a bump, too much and you may miss to have a clear motif.
Also in some cases there's an opposite of build up, more like a motif "has a sense of ending" that makes the listener be curious about another motif.
So, is there a general rule-of-thumb/well-researched theory on build-up/signaling change in pop compositions?
What keywords should you use to search for materials discussing it?
(Feel free to edit my question regarding jargon - I have learnt my theory mainly in Hungarian).