I have smart playlists for genres and for star ratings (1-5). The way the star ratings work is as follows (keep in mind that I mostly shuffle the entire library while on the go when reading how I interact with the library):
1 star | This is something to delete (from the days before I could do that on-device); I don’t have anything that’s 1 star anymore because we moved on
2 stars | This got my attention and made me check my device to find out the song / artist; this song is something special
3 stars | These are the bangers of my library
5 stars | There’s nothing better
I don’t use 4 stars; therefore, everything is either no stars (meaning normal) or 2, 3, or 5 stars.
The rule is that if I check my device to find out the song / artist and the song doesn’t already have a star rating, it automatically gets promoted to 2 stars. If it already has a star rating, it goes up by one, from 0-2, 2-3, or 3-5. This system works perfectly for me, such that when I bumped a song from 2-3 stars the other day, I said to myself, aloud (in my car), “the system works!”
I either select a genre and shuffle / randomize or I select a star rating and shuffle / randomize or (most often) I choose the entire song library and shuffle / randomize. This works well enough that I have no need for manual playlists. The only exception to this was creating a playlist for a dinner party where all the guests were other couples and the music was highly curated for a single evening.