Can you start anywhere in chairs? Diaxial strain?

[Kiara1F]

Can someone explain the explanation for this chair? What does it mean to limit 1,3 diaxial strain?
Why didn't the solution just explain that the biggest substituent is equatorial? And why did the positioning start on that particular equatorial area instead of the one above where it would be (axial up) and equatorial down.. why did it skip down to the next carbon? Or does it not matter and you can start anywhere?

[Chem_Mod]

Where is the chair?