As of SERVER-72440 we execute unbounded user collection scans with low storage admission priority. However there are some edge cases where we may end up deprioritizing a scan which isn't actually unbounded. For instance the following pipeline:

[{$unwind: "$foo"}, {$limit: 10}]

Such a query isn't particularly useful as it uses a limit without a sort, so we accepted this limitation for the time being. But it would be good to go through the remaining edge cases so that the behavior is consistent.