Kinda depends for me. With lyrics I like to focus on them til "first draft" . That could be hours or days. Generally, I have a pretty good idea of the melody when the lyric is at that point. Most of my draft lyrics I like to put out on the critique boards. Making some adjustments when I can see the issues. Sometimes I need a walk away to let a critique sink in.
When I start on the music bed, I lay different tracks, sometimes different days, different instruments.. generally in order drums, piano/keyboards, strings or brass, etc. Then bass, guitar..Those take awhile because I don't play those instruments and have to work on a different timeline. I sometimes put these out for critique before moving forward.
So I can work on multiple songs at a time during that period.
When the bass and guitar are pretty solid, i work on the vocals. If it's a male vocal.. there's another wait period..
Once vocals are started, I don't work on much else but the one song. When i start on mixing the bass, guitar and vocals into the bed, I mostly only work on that song.
I have many lyrics not set to music yet and several music beds without the guitar, bass and vocals.
Probably not the most efficient but that's how it works, or not works, for me.