Well, it's an interesting question.Is that what they need to lay..? Mine lay all winter.. on about 11 to 11 and half hours of daylight.. quite a few of mine weren’t laying this winter because of molting.. but most are back laying now..
Some you can read say it's the number of daylight hours; more daylight hours, more likely the hen will lay. This it seems is the basis for people adding light to their coops to maintain/increase production. If it was as simple as this then there shouldn't be any hens laying when the days are at their shortest.
My friend in Finland gets very short days but his hens still lay eggs.

Here, the local keepers will tell you it's not the daylight hours but from what I can translate, it's the quality or intensity of the light.
The truth seems to be that nobody is really quite sure how it works despite all the studies.
Science believes it understands the basic mechanism but....
Btw, one thing science and peoples observations have proven is that moulting is not directly connected to egg laying.
It's a bit like the statisticians who can prove that blue flashing lights cause accidents. The blue flashing lights and the accidents are coincidental but not dependent.