Now we're really taking the analogy apart until it's no longer reasonable, but I'll continue:
Sometimes it makes sense to stand around waiting for the burger to cook. Maybe all you have to do are low-value burgers and it's nice to maintain an idle chef for any high-priority burger tasks that come in.
Or there are important but non-burger tasks that need to be done but are easily deprioritised in favour of burgers.
Where it really falls apart is that a restaurant has a predefined menu and no items are allowed to have unknown complexity (someone asking items out of menu just gets a “no”). Estimates are based on actual measures, not guesses.
There will be accidents, but those will be rare enough to not have to be planned for.
In that respect, a restaurant queue is a lot more akin to a factory, and is fundamentally different in nature.
Sometimes it makes sense to stand around waiting for the burger to cook. Maybe all you have to do are low-value burgers and it's nice to maintain an idle chef for any high-priority burger tasks that come in.
Or there are important but non-burger tasks that need to be done but are easily deprioritised in favour of burgers.