The unfinished piece may need a different day rather than a harsher opinion.

Being stuck feels like a verdict on the work when it is often just a report on the hour. Tiredness, a low mood, too many days in a row on the same thing: all of these produce the same sensation, which is that the piece is no good and you were wrong to try. The work has not changed since yesterday, only your capacity to see it.

When the criticism in your head gets loud, stop and look again after sleep rather than deciding then. Put the thing away without a conclusion. If it still looks wrong on a good morning, then it is genuinely worth changing.