MBL value will increase the length for all metadata values being returned for each result. Given that there's a very large number of metadata fields available in v14+, and the
num_ranks value doesn't have an upper limit (by default), you could request some very large responses from the query processor, even before they hit the templating layer.
Ideally, you'd want to do all you can to keep the search response packet as small (<200KB) and fast as possible (<200ms) - a multiplier effect kicks in, otherwise.
Search Response Size = baseline data model + Number of fields in
SM is either
num_ranks x avg. metadata field length
You may want a single-result query to return the entirety of a series of a very large metadata fields, for example: