The method of taking visual bearing is most often not necessary and would be too much workload in high traffic areas where multiple ships need to be tracked.
In heavy traffic bearing change can be observed visually without taking a bearing. Typically the only time a bearing is used is to ensure that the ship under visual observations matches (same bearing) the one being tracked by ARPA.
Typically ships which have potentially have risk of collision are identified by eye then the vector is checked (or a plot is started) on ARPA.