I used to do the same thing I myself with each completed repair/restoration I did. As soon as one was completed I was making a track solely on that synth. If I couldn’t squeeze all the parts out of a single instrument (drums sounds on a string machine is particularly tricky!) I’d use the bare minimum of just what I needed. Sadly many of the tunes and parts were lost in a HD crash and I hadn’t backed them up. It’s a really good exercise in getting to know a new synth and finding new ways of programming.
For me the natural progression was to replace some of the weaker parts but still base the song around one synth, trying to get what I could out whilst still trying to come up with a ‘rounded’ end product. That led me off in more new musical directions!
Some songs that stick in my mind (and didn’t go to the big HD in the sky) we’re an unashamedly 80’s sounding JX8P tune, a darker progressive house tune done on a DW8000 and quirky little ditty on a Korg PE1000. All different and all ultimately influenced by the instrument and me experimenting and finding agreeable noises! Good fun and highly recommended.