For myself, I try to organize my smartphone use into “blocks”.
I don’t use it in the morning (~ 1 h after waking up), and I can honestly vouch for this strategy - mind feels much more focused and calmer if you start your day with books or mindful activities such as walks, showering, exercising or cooking an amazing breakfast
At work, I also try to limit its exposure as I find it distracting.
My primary “smartphone time” comes in the early evening when it’s time to communicate, catch up with some news or articles or listen to some audio content.
When it comes to evenings, especially around 1-2 before going to sleep, a smartphone is an absolute no-go - it disturbs melatonin secretion and engages your mind in a distracting, sleep-disturbing way. A habit to charge your phone in a different room is a life-changing one.
In the end, what I found out is that intentionality is extremely important - you need to know when do you want to use your phone, and what do you want to do. This leads to another insight - planned “no smartphone” times, require you to think about other activities, forcing you to do other, more productive (or more valuable) activities (like reading)
Amazing thing is that the more you limit the use of your phone, the more you like it and the less you want to use it!