I use "tab-tab" auto complete to speed through refactorings and adding new fields / plumbing.
It's easily a 3x productivity gain. On a good day it might be 10x.
It gets me through boring tedium. It gets strings and method names right for languages that aren't statically typed. For languages that are statically typed, it's still better than the best IDE AST understanding.
It won't replace the design and engineering work I do to scope out active-active systems of record, but it'll help me when time comes to build.