The method you describe is old school, dating back to a time when there was no other way to do it. Today, it's no longer necessary. A full-featured delay plugin can achieve almost exactly the same end with the simplicity of a single insert or buss effect.
The bundled Sonitus Delay doesn't have as much versatility as the 2-bus-2-delay method, because you cannot effect the left and right delays independently. But it still does the job 99% of the time. For those rare occasions when it doesn't, you might consider something like the ridiculously-versatile Timeless2 from FabFilter.
But if you really need to effect each delay channel separately, it can certainly be done with two busses and two delays. You'd use the plugins' internal feedback rather than routing to achieve the actual delays, though.
P.S. as for the suggestion that "many" professionals use the bus method, I doubt it. The statement may have been true 30 years ago, but I'd bet that the vast majority of pro mixers today would just stick in a delay plugin.