What did you have for breakfast last Tuesday? How many eggs are left in your refrigerator?
If you had any trouble answering those questions, you will understand why memory is not a reliable tool for processes. People get distracted and skip steps. Requiring people to remember counts can be especially disastrous. It is easy to lose one’s place and come up with the wrong number, especially when the counts are highly repetitive (i.e. counting the number of items to put into a 10-pack).
It is far better to make the process and workstation design drive standardization than a person’s memory. Place tools in the sequence of use. Use kits to make sure all parts are installed. Use a scale to weight counted items. It doesn’t take much effort to remove the requirement for memory from a process.
Keep this in mind: making a person use their memory is extremely disrespectful to them. It is not a matter of if they will forget something, but when. Creating a process that is guaranteed to fail sets up team members for confrontation with their leaders or peers when something goes wrong.