I'm not sure anyone completely understands your line of questioning. That is why there have been no answers.
Strabismus is a rather broad topic. I'm not familiar with the term "squint" in relation to strabismus. Are you referring to degree of deviation of the eyes? If so, are you talking about eso-, exo-, or hyper-deviation?
As a general rule, fatigue worsens strabismic deviation, because the mind loses focus on maintaining alignment of the eyes. In fact, someone who does not even have strabismus will have an outward deviation of the eyes when near sleep. This is the relaxed state of the eyes.
Hope this addresses your question. If not, you need to rephrase.