On lawns under 1/2 acre, it is easy for me to line up with the previous pass by looking for where the grass is wet from the spray. Anything big or tricky gets marker dye added to the tank.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738