Fast forward to 5 years and more than 100 Squarespace websites later, I believe I’ve gained essential skills and streamlined the entire process to push the artistic boundaries of Squarespace. And it is my joy to share it with fellow designers and business owners. There's a lot more to learn as Squarespace is a very dynamic platform and company. I hope somehow my process tricks would help other designers and website builders.
Here are two gamechangers in my design workflow:

Learning Adobe XD to mock-up my designs.

Using Squarespace Extension PRO to duplicate my sites.