This is true for almost everything and particularly gardening. Many a pest outbreak can initially be squashed between finger and thumb but before long eggs have hatched and the maggots departed all over the plants where they cannot so easily be picked. Indeed much of the skill and relaxed attitude of the 'good old boys' is that they’re well aware of the timing for each and every operation.
We learn by making mistakes
They know just how long they can let weeds grow before they must hoe, when to sow what or prune this and that. Much of this knowledge comes with a few years experience. We learn by making mistakes, by doing the right thing at the wrong time and doing the wrong thing at the right time.
Each permutation giving different results. It doesn't matter as long as we do learn from the experience and so can do better the next time. Basically it’s much like learning to drive; initially it’s all panic, but soon things make sense and before long you’re looking further ahead and all becomes automatic. Until then you may find useful some tips and reminders of what must be done and when.