Often, a bottleneck is highly visible through daily monitoring. If you do not work with the process, you may be ask those who deal with the process on daily basis. Data often shows where the queue is growing by simply reviewing volumes of unprocessed items.
Once bottleneck is identified, it is often best just to pour immediate resources to help solve it while also working in parallel on a process improvement solution. This can be often done in phases whereby first you just clear the queue with more people, then implement a tactical short term enhancement to the bottleneck, and finally develop an automated strategic solution so the bottleneck never occurs againHow to spot a bottleneck diagram. This is one of the top business frameworks encompassing strategy, project management, IT, internal processes and client experience.