I found all the dates of the NBC reruns of "Columbo" on a website called Ultimate70s.com. I'm not sure if anybody here is interested, but I thought I would share what I found:
Murder by the Book--3/8/72 and 6/28/72
Death Lends a Hand--4/12/72 and 8/2/72
Dead Weight--4/26/72
Suitable for Framing--5/24/72
Lady in Waiting--8/16/72
Short Fuse--7/26/72
Blueprint for Murder--9/6/72
Etude in Black--4/15/73
The Greenhouse Jungle--8/26/73
The Most Crucial Game--5/27/73
Dagger of the Mind--5/6/73
Requiem for a Falling Star--7/15/73
A Stitch in Crime--6/17/73
The Most Dangerous Match--7/29/73
Double Shock--8/12/73
Lovely but Lethal--12/23/73
Any Old Port in a Storm--8/11/74
Candidate for Crime--6/2/74
Double Exposure--3/31/74
Publish or Perish--7/7/74
Mind over Mayhem--5/26/74
Swan Song--9/8/74
A Friend in Deed--12/29/74
An Exercise in Fatality--3/16/75
Negative Reaction--8/17/75
By Dawn's Early Light--5/11/75
Troubled Waters--6/15/75
Playback--8/31/75
A Deadly State of Mind--8/3/75
Forgotten Lady--3/14/76
A Case of Immunity--5/16/76
Identity Crisis--5/9/76
A Matter of Honor--9/12/76
Now You See Him--6/20/76
Last Salute to the Commodore--9/5/76
Fade in to Murder--6/12/77
Old Fashioned Murder--6/26/77
The Bye-Bye Sky High I.Q. Murder Case--9/4/77
Try and Catch Me--6/23/78
Murder Under Glass--7/31/78
Make Me a Perfect Murder--7/9/78
How to Dial a Murder--8/7/78
The Conspirators--9/1/78
I also looked at the dates for the other "NBC Mystery Movie" series. There were some peculiarities. The strangest thing I noticed was that there were 20 preemptions during the 1976-1977 season, almost as though NBC were trying to run the series into the ground in order to cancel it. Anyway, it's a fun website to poke around on.
What I think is interesting about it is how totally random the reruns appear to be. They show them in no particular order, and there often times isn’t a true rotation with the other mystery movie series. The reruns of 1975-76 are maybe the oddest. No episode of “Columbo” (new or rerun) aired at all after November 2 or before February 1. But there were three “Columbo” telecasts in a row on May 2 (new episode), May 9 (rerun) and May 16 (rerun). There was a rerun on June 20 and then no other “Columbo” telecasts at all until September 5 and 12, two weeks in a row at the very end of the summer. Was this a network strategy or just totally random? “McCloud” and “McMillan & Wife” have some bizarre patterns at times, too.