The final task is to revise the question I posed at list rearrangement:
I now start with this list:
lis = {{1,2,3},{"True",3,4,5},{6,5},{3},{6,4},{"Truex",2,1},{5},{5,6},{7,8,9}}
I want to make a new list consisting of elements of lis that begin with "True" (or "True" followed by any further string characters), and include the next two elements directly following, thus making triplets:
res = {({"True",3,4,5},{6,5},{3}},{{"Truex",2,1},{5},{5,6}}}
Again the task seems to be to get SequenceCases to recognize the pattern that allows it to pick up elements with "True" as well as "True*" Thanks again for ideas.
SequenceCases[lis, {{_?(StringContainsQ[ToString@#, "True"] &), ___}, _, _}]
$\endgroup$