Knowing counterpoint can help you understand why you're not getting the sound you want but if you're writing in a modern style, it's not so important that you slavishly follow those rules. OTOH, if you're trying to write Baroque music, then you have to be more picky.
So it becomes a case of breaking the rules in places where you're not going to hear the broken rule! Say you're writing something cinematic and you've got parallel fifths (a counterpoint no-no) moving in the low parts, changing once per chord. But on top, you've got two melodies, a main one and a supporting one. With those melodies, you wouldn't want to be writing parallel fifths when you harmonize the main melody because that will really stick out.
There's also the concept of "sectional antiphony" which was a huge arranging technique in the big band era. What happens here is that you may have one section moving in homophony (parallel chords) while another section does the same thing but with a different melody. It's also homophonic but the effect of the two sections playing together is that they are creating a sort of counterpoint between them, even though within each section there is little or no counterpoint. And a lot of the time, each section will be answering each other, with a little bit of overlap, hence the term "antiphony".
Counterpoint is much easier to create when one melody is relatively busy compared to the surrounding ones. So long lines against the busy melody become an easy source of counterpoint. By the same token, the main melody could have all sorts of busy "filigree" around it, also in support. Things like flute runs that dash around while the main theme is chugging along more slowly would be a good example of this.
You can combine these approaches too, using some counterpoint along with homophonic sections and sectional antiphony.
And finally, there's the "pass the torch" technique, where a melodic idea is taken over by another instrument waiting in the wings. Here, the new instrument overlaps the same last note or two from the melody that was handed over to it from another instrument. This is a great way of using and introducing new sounds without them being too abrupt. It's not counterpoint but it is a way keep all the instruments in use.
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