An emergency fund buys the right to have an emergency without immediately having another one.
STILLNESS
STILLNESS
Without a buffer, every problem becomes several. The car breaks, so the payment is late, so the fee is added, so the next month is short, and one event turns into a cascade. Savings do not prevent emergencies, they prevent an emergency from generating more of them, which is a different and more important function.
If you can put anything aside, even a small amount held for this purpose does disproportionate work. Keep it separate and slightly inconvenient to reach. And if you are currently in a cascade, the priority is stopping the chain rather than solving everything at once.
What margin do you keep so one bad week stays one bad week?
Free, with nothing to buy inside it.