Chains can be super quick. They’ve basically made stores into kits. Once they’ve got measurements for the space, they pick the components that fit, a contractor installs and it’s up and running.

They do this for redesigns too. They can retrofit a place in a week or so even keeping it running during the day and working overnight.

A crazy amount of engineering, design, architecture, etc must go into planning to minimize modifications to meet code in various places etc.