I'm a current Googler with C++ readability and I can confirm, you're absolutely allowed to write templates in "leaf node" projects and it's encouraged, especial

I'm a current Googler with C++ readability and I can confirm, you're absolutely allowed to write templates in "leaf node" projects and it's encouraged, especially in cases where templated code reduces error-prone boiler plate. Heck, there are whole Grow classes dedicated around learning how to use variadic templates.