Hello There.
Involving many transactions per day you are right to make automation scalable in a robot pov.
In term of architecture the REF is always best approach, but more is to separate dispatcher as a dedicated automation ( Will insert items to queue that will generate the 2000 transactions ) and a performer as another automation.
One possibility that can be used in your scenario is to setup a queue trigger on the queue filled in the dispatcher automation to run the performer,
and specify the Maximum number of pending and running jobs allowed simultaneously to more than one to make it scalable. ( Two bots running simultaneously processing items )
Hope that helped !