eople sometimes get split across teams when working agile (or Waterfall, for that matter). You might hear things like “this team has two front-end developers, two back-end developers, a UX designer, a tech BA, and 50% of an architect”. Why 50%? There are usually two reasons:
The team doesn’t need a full-time person working in that role for the current scope of work, e.g. the team only needs about 20 hours a week of someone providing an architecture (or UX or DBA or whatever) role, but that person needs to fill in 40 hours (or usually more) of work per week.
There aren’t enough people in that role to go around. This is quite common: you have four scrum teams, and two of role X (BA, Architect, whatever). The solution seems simple: you split them 50 / 50, each team gets one half of that person.
Why splitting people across teams is a bad idea
There are a few reasons why people split across teams should be avoided if possible.
Ceremonies take up a higher proportion of a person’s time.
I think the Scrum ceremonies are all important and should be followed unless you have specific reasons not to do so. They do take up a decent proportion of your team a week, but their purpose is to reduce the amount of time in meetings, by shortening communication loops. If you put a person on a second team, they need to attend all of that Scrum’s ceremonies too.
That means the proportion of time remaining in the sprint for their primary activities decreases. You can imagine what would happen if you tried to put a person in a third or fourth scrum.
If someone doesn’t attend the ceremonies, they will miss out on vital communication loops (from standups) and feedback/inspections (sprint reviews and retrospectives), not to mention planning and estimation (sprint planning).
If someone is working in multiple teams, their attention will be split. People are not as efficient at multi-tasking as many think. Context switching has a cost. It certainly reduces productivity and effectiveness.