Huge numbers of postgres installations are on small machines and/or machines shared with other software. And whether you want a large work_mem hugely depends on

Huge numbers of postgres installations are on small machines and/or machines shared with other software. And whether you want a large work_mem hugely depends on whether you want to run an OLTP workload with a few hundred connections, or an analytics workload with like 2. It ain't as simple as you paint it.