There is a pattern Converging and Diverging in Architectural Lens described as:
Can you channel people so they come together (or split up)?
Gates (and gatehouses) channel visitors through a narrow opening, allowing a toll to be levied, or to help control potential threats.
Every manager should use this architectural solution in everyday life. This design trick helps to optimize the work flows. Grouping and ungrouping save the most valuable asset – your time.
For example, if hiring three new people this month do your best to have the same start date for all three. Thus, you are able to save time on introductory trainings, adaptation lectures and other activities. You are doing it once for all of them and not three times for each one.
The same technique I would recommend to use with emails. Every manager is overloaded with them. Save your time by building the rules that group emails into folders. Based on sender, receiver, topic, project, distribution list or whatever. Don’t proceed them immediately. Read you inbox once per hour or even less frequent. As soon as your messages are grouped you can work on specific work streams and not on a single email. You have no switch of context. Thus, you are acting more effectively. And you have the picture of the work stream in a one place.
Splitting the single work stream works brilliantly in many cases as well. E.g. it is useful to split one meeting into two in case if agenda has two separate work streams. Even if the list of attendees stays the same. It helps to concentrate, prepare and focus on a single topic. It makes the meeting far more effective.
The same technique is applicable to email writing. You can split an email into two different threads if there are several topics discussed at the same time. And you can merge a plenty of emails back into single follow-up message to outline the list of actions outstanding and focus on an implementation and not discussion.
Disclaimer: be careful when grouping people. It might be perceived unfair. Even if it is not. One consider himself as a unique person. And that is absolute true. Always care about people and their feelings. The same problem when team is jelled and it is pain for them to be splitted. Take care of people. Always.