Flag life is two separate problems that get discussed as one, which is why the answers people are given are so vague.

Wind is a hem problem

Wind failure always starts at the fly end and works back. It is a stitching specification, not a fabric one: four rows of lock stitching at the fly, a reinforced header, and double stitching all round.

Exposure multiplies it. A flag on an open junction does several times the flexing of one in a sheltered forecourt, and the same flag will give very different answers in the two places.

Sun is a fabric problem

Colour loss is ultraviolet, and no amount of stitching helps. Reds and purples go first, which is unfortunate for campaign artwork.

Ask what the fabric is and roughly how long it holds colour in the open, and specify a UV-stable polyester for anything running past a single cycle. A flag that is structurally perfect and visibly pink is still a flag you have to replace.

Speed is a third problem

A flag on a vehicle is in a sustained gale that never drops, which is not the same as weather. It needs a heavier denier, taped double-turned edges and a shorter fly relative to the header so there is less leverage on the free edge.

A standard pole flag on a truck shreds in a drive or two, and it is not a manufacturing fault. It is the wrong build.

What to do about it

Buy the hem for the wind you have, the fabric for the months you need, and a separate build for anything that moves. Then rotate: a spare set swapped in halfway through doubles the life of both.

Keep the artwork on file so a replacement run is one email rather than a project.