This both groups the tabs logically, and also improves the workflow by causing closed search results to go back immediately to what you were doing.

It's a very common workflow after a search to want to return to the page you were on when you executed the search. This may be to refine your previous search that was unsatisfactory and execute it again with new criteria, or if you got what you needed from the search, to simply continue on with what you were doing.

Instead, Gnucash currently simply dumps the search tab on the far-right, causing a closed search to dump you onto the next farthest right tab, which is frequently something not relevant at the moment.

Browsers have similar issues, and have similar optimizations to make tabs smarter and easier to work with. Gnucash should seek to emulate these ideas.