I work on residential and light commercial, split systems and rtus mostly under 10 tons.
I use the drain dawg, the drain kat, a wet vac and occasionally a water hose (on rtus after cleaning the condenser coils). It all depends on the situation.
I prefer blowing it out with the drain dawg but it's not alway practical especially in medical clinics with split systems and shared drains terminating under bathroom sinks. A wet vac is essential then.
I'd like to see a clean out tee above the p-trap. Makes blowing out most systems easy.
Just cap the vent and blow away.
A wet vac or drain kat can work just as well if it's easy to access the drain end and are a godsend if unable to cut into the drain due to access issues..
Just cap the vent and clean out first and uncap the vent afterwards.