transactions – How do exchanges automate transfer of Bitcoin from cold stoarge wallet?

Most exchanges use Cold Storage to store the bulk (approx. 95%) of their user assets. Only a relatively small amount (approx. 5%) of funds are held in their Hot Wallet.

My question is, what process is used to transfer funds from cold storage to the hot wallet? Is the process automated in any way or is each transfer reviewed and processed manually? It seems to be very tedious and inefficient to have to review & process each transfer manually without any form of automation.

So my question is: Is there any way to make the process more efficient? Are there generally well accepted protocols that most exchanges follow in this regard?

Thanks