Yes, perfection does exist… in some works of art, but not in the garden. There is almost always something not quite right about any kind of planting: insect holes in a leaf, powdery mildew on lower leaves, a brown spot here and there, etc.
While many gardeners immediately reach for the most powerful pesticide they can find at the first sight of a problem, they’re usually wasting their time. Often the insect that drilled the holes is already gone and mildew is usually the final stage of a disease that started weeks before and has already stopped spreading, so why bother? When the disease or insect or “problem” is minor or out-and-out inconsequential in the long run, no treatment is really necessary. At any rate, a few pierced, chewed, spotted, or swollen leaves don’t really disfigure the garden, at least not if you squint a little.
That’s why I suggest you apply the “15 pace rule”. It couldn’t be simpler! Before treating, step back 15 paces: if you can’t see problem at 15 paces, it’s probably not a problem worth treating!
Among the problems that are trivial and rarely worth reacting to are leaf miners, late season powdery mildew, leaf and stem galls, and yellowing lower leaves.