I see this all the time in the landscape. People correctly position their mower wheels right next to the curb and cut their lawns. All season!? Mowing like this creates deep grooves, or ditches, in the lawn which isn't good. It detracts from the nice, uniform green lawn space we expect.
What's the solution? Stop putting your mower wheels right against the curb. Move your mower over a little bit. Yes, it means that you'll have a bit more to line trim later but it's a small price to pay.
The boulevard pictured above is mowed correctly north-south along the longest line. But small residential lawns can be mowed east-west and diagonally, so don't be shy. Never let deep grooves develop in your lawns. It looks awful.
Don't be a slave to your mow lines.
Vas Sladek, B.Sc., CLHT