im interested to know what the end goal is. for example
MATCH (a) WITH DISTINCT LABELS(a) AS temp UNWIND temp AS LABELLIST
WITH LABELLIST
MATCH (n:LABELLIST)-[:managed_by_process]->(m) return m;
appears to be
line1: traverse all nodes and collect all distinct labels for all nodes and then unwind from this set each label
line3: for each label find all nodes for this label see if it has a :managed_by_process relationship pointing to any other node and then return this any other node.
Why not simply
MATCH (n)-[:managed_by_process]->(m) return m;
which says, traverse all nodes see it it has a relationship named :managed_by_process pointing to some other node and then return that other node?
just a note that your queries though valid are performing a allNodesScan. so if you have 100 million nodes, then each time you run the query then we will traverse all 100 million nodes.
Now if you changed for example
MATCH (n)-[:managed_by_process]->(m) return distinct (labels(n)+m.guid)
to
MATCH (n:mail)-[:managed_by_process]->(m) return distinct (labels(n)+m.guid)
and of the 100 million total nodes in the graph, if only 8 million had a label of mail then we would only travese 8 million nodes