An oscillator cycles between states, or varies periodically, like a pendulum that swings back and forth, or like the rotation of the earth, or the vibration of a piano string.
Human beings oscillate in many ways. Whether by breathing, or sleeping, or the beating of our hearts, our lives are full of cycles.
Coupled oscillators influence each other and tend to synchronize. If you can tie your practice to one of these, the natural oscillation will tend to reinforce your practice. But I suspect that if practice is free floating, it is less likely to be accomplished, or may even be dampened by the other rhythms of your life.
The most likely times for practice are at or near those times that are “fixed:” when we get up, just before we eat, just after work, and just before bed. Even though we may do those things at irregular times, we generally do them every day. They can serve as anchors in our mind, “Ok, now it’s time to get up and meditate, or go to lunch and run, or go home and play the piano, etc.” These times of day are themselves oscillators that we can set our biological practice clocks to.
On the other hand, those are often times when we’re hungry and our will power is correspondingly low. When I’ve failed here, it’s usually because I succumb to hunger. So maybe we eat something like an orange or apple to tide us over.
Carving out multiple times in the day for practice isn’t easy. There aren’t a lot of polymaths walking around. Having a biological, circadian rhythm to tie them to can make it more likely they get done.