7x7 centers

[riffz]

I use blocks and my opinion is worthless.

 

[Joker]

My opinion is worthless for 7x7 also.

 

[Dene]

I voted lines which I use as priority. I never go for the inner 3x3 square then expand outwards anymore however what I sometimes end up doing is going for the 3x3 block in the corner, then expand that to 3x4 then 3x5 so it's the same as having done the inner 1x5, expanded to 2x5 and then 3x5 onto one side as opposed to going for the inners then outers afterwards. Occasionally I will also go for the inner 3x4 block if it's convenient, then expand out to 4x4, 4x5 then 5x5.

 

[qqwref]

Sub-3 should be possible on 7x7 if yours turns well enough.