This depends on how many bank accounts you have and how many transactions are in each account. Generally speaking, for new-ish business owners with 3 or less accounts, it should only take you about 20 minutes each month if you use my automation techniques. Also, the more you do it, the faster you'll become.
That being said, the more complicated your finances are, the longer it’s going to take. For example, if you have more than 3 bank accounts, if you mix your personal and business finances, if you use multiple payment processors (Shopify, Stripe, PayPal, etc.), it will likely take you longer than 20 minutes. You can still automate the majority of the work, but these things may cause your month-end process to be a bit longer. But, again, the more you do it, the quicker it will be!