I'm often astonished by the inefficiency of project delivery, particularly in large companies.
Teams spending months building sub-systems from scratch, where there is an off the shelf(sometimes open source) tool that will do the same job and better.
Man years of work going into chasing trends like "serverless" or "microservices" for no real reason, when a monolith running on a server, could be delivered in a fraction of the time and probably do a better job than what ended up being built.
I'm convinced that paying two teams to work on the same project would often cost less than paying for the huge teams and cost overruns I've seen.