Standard work is the currently best, agreed way of performing a task — documented so precisely that deviations can be seen, and improvements have a fixed starting point. Without a standard there is no deviation; without deviation, no learning.
The standard is not an instrument of control but the foundation of improvement: you cannot improve a process performed in five different ways — you don’t know what you are improving from. That is why standard work is the prerequisite for kaizen, not its opposite.
A good standard is owned by those who use it, hangs where the work is done and is revised each time a better method is found and verified. A standard unchanged in two years is a warning sign — not a mark of quality.