I used to be a public defender before I went into corporate and tax practice. Out of roughly 100,000 cases that went through the local PD office while I was there, fewer than 10 involved parallel construction.

Including the two neighboring counties, out of nearly 750,000 criminal cases during that time, only about 3 or 4 dozen involved parallel construction, and most of those were gang cases in which the parallel construction involved one of the gang members turning on his homies.

It's big news in local legal circles when the prosecution tries to use parallel construction to get evidence into the record because it happens so rarely.

It does happen more frequently at the federal level, but they also have significantly more resources to conduct investigations along parallel paths.