The point of the proverb is that it is not possible to temporarily exempt yourself from the paths of wisdom and then return to them when you like, and still think that you are on the right path. At face value the proverb makes a self-evident point and we wonder why it needs to be made – a man’s reputation depends on his behaviour.
Let us not say when we are exhausted in the way of righteousness, I will allow myself some liberty to commit this sin for a short time, in order to remove the pressure of constantly having to deny this particular ungodly lust. I will neglect my Christian service today and not go out with the evangelistic team, because I am feeling spiritually down. After that brief rest, I will return to the work and will be strengthened to walk before the Lord more vigorously than I did before. That is not going to happen. Instead you will be even more likely to abandon your spiritual duties and give way to the weakness of the flesh again next time.