An idea often suggested, such as here
https://forum.smallgiantgames.com/t/add-more-team-slots-4-5-6-as-well/3440/8
Personally I only use 3.
With war and raids I customize each team as best I can for the opposition, so having more saved teams is irrelevant.
One for defence, one for current titan and one for farming suits me. Everything else is bespoke.