A few years ago I made a large batch of eclairs (like 8 dozen) and wound up making about 6 batches of pastry cream (several of them gluten-free, to go in gluten-free eclairs). With practice, the prepping/cooking part is not where you spend the most time.
The most time-consuming part of making pastry cream is chilling it, and spreading it fairly thin on a sheet pan then putting it in a blast chiller is one way cooking competitors have to speed that up. Using a drum sieve to strain it saves time, too.
And they don't usually wait for it to get fully chilled and set, they just get it down to about 80. An extra egg yolk or two will produce a fairly firm pastry cream even when it's tepid. I have discovered, though, that it is possible to have a pastry cream get too eggy, it tastes more like scrambled eggs than pastry cream.