Playing In Time = Listening
It’s challenging to perform a piece of music. There are techniques (precise bending, tongue blocking, articulation, etc.), movement (conjunct and disjunct), dynamics (volume and tonal), rhythm (individual licks and their chaining together into phrases) and everything else involved in playing a particular piece of music well.
The key to playing in time with other musicians (whether to a metronome, jam track or live band) is in knowing your music well enough (with all the elements mentioned above) that your focused attention is not on what you’re playing, but what the band is playing and how what you play fits with it.