We recently had management ask for some diagrams of our applications infrastructure. Draw.io made that so easy with their pre-made components and export to PDF. Will definitely use it again.
I was at Amazon working on something - their own engineer was using draw.io to quickly grab AWS icons for Lambda, IoT core, API Gateway etc and place them into his flow chart.
He said they had a library somewhere of AWS artwork, but it was easier to just use draw.io’s art lib.