Even as a professional EE working on high speed digital and mixed signal designs (smartphones and motherboards), I used reference designs all the time, for almost every major part in a design. We had to rip up the schematics to fit our needs and follow manufacturer routing guidelines rather than copying the layout wholesale, but unless simulations told us otherwise we followed them religiously. When I started I was surprised how much of the industry is just doing the tedious work of footprint verification and PCB routing after copying existing designs and using calculators like the Saturn toolkit.

The exception was cutting edge motherboards that had to be released alongside a new Intel chipset but that project had at least a dozen engineers working in shifts.