A typical approach that a lot of people take to practicing guitar is to play through everything they have been working on from start to finish. This can be fun, but this isn’t practising.
So what is practising? What are we trying to achieve when we practice guitar?
We are trying to push things into our subconscious. We are working towards mastering whatever it is we are working on. We accomplish this by breaking the piece / exercise into tiny sections, working on them individually, and slowly reconstructing the piece from the elements that we have been practising.
Practising and playing guitar are two different things.