In late November of 1973, ABC Network overhauled its Friday lineup, cancelling fifth-year veteran Room 222 and freshman Adam's Rib at midseason to make room for The Six Million Dollar Man. The Six Million Dollar Man occupied a really unusual timeslot for a one-hour drama: Fridays at 8:30 to 9:30 PM Eastern. The Brady Bunch stood pat at the 8 PM lead-off position while the 1970 version of The Odd Couple was shifted from 8:30 to 9:30. Three pilot movies of The Six Million Dollar Man aired on March, October, and November of 1973. Six Million Dollar Man wound-up ranking eleventh for the entire 1973-74 American broadcast TV season with a 22.4 average rating. Here are two examples of the figures TSMDM pulled for two of its first-season originals:

February 8, 1974 ("Operation Firefly") (https://www.worldradiohistory.com/hd2/IDX-Business/Magazines/Archive-BC-IDX/74-OCR/1974-02-18-BC-OCR-Page-0040.pdf): 24 rating/36 share
February 22, 1974 ("Little Orphan Airplane") (https://www.worldradiohistory.com/hd2/IDX-Business/Magazines/Archive-BC-IDX/74-OCR/1974-03-04-BC-OCR-Page-0029.pdf): 24.8 rating/37 share

For its second season, The Six Million Dollar Man slipped to an average of 17.1 and 51st place, thanks to being placed between Kodiak and The Texas Wheelers (both of which were cancelled after four episodes due to extremely abysmal ratings) at the beginning of the 1974-75 broadcast season, and recovering once it moved to Sundays at 7:30 to 8:30 after its January 19, 1975 original. For its third season, TSMDM slid to airing on 8:00 to 9:00 PM on Sundays, and it ultimately ranked ninth for 1975-76 with an average of 24.3, and then seventh for 1976-77 with a near-identical 24.2 average rating. TSMDM's fifth season saw its ratings slip to 40th place and an average rating of 18.8, thanks to moving to the Mondays at 8 hour from Sundays at that same hour to make room for the TV adaptation of How the West Was Won for TSMDM's final six episodes.

Can you think of any reason ABC made such an odd schedule placement of a Top-20 show?

Sanford and Son was a smash hit. ABC was probably trying to avoid having Six Million Dollar Man face it directly, and also get Sanford and Son viewers who weren't watching its NBC leadouts. But when Chico and the Man hit ABC must have decided to move Six Million Dollar Man to Sundays.

There are at least two veteran hour dramas, both of which are on CBS, that also aired from 8:30 to 9:30 pm.

In the years following the Rural Purge, the 1968 version of Hawaii Five-O was slotted on Tuesdays at 8:30 to 9:30 in seasons four, five, and six, before it slid to 9:00 to 10:00 for season seven. It was scheduled after Maude (a 30-minute sitcom) for seasons five and six.

During its sixth season, Simon & Simon was slotted on Thursdays at 8:30 to 9:30 for three episodes (on December 4, 11, and 18, 1986). The 1985 version of The Twilight Zone led-off Thursdays (at 8:00 to 8:30; it had been reduced from an hour to a half-hour at this point), and Designing Women aired at 9:30-10:00 (DW would have one more original airing on January 1 of 1987, before moving to Sundays at 9 after February 1). Simon & Simon aired on Thursdays at 8:00 to 9:00 for the first nine episodes of that sixth season (before November 20), and slid to 9:00 to 10:00 for that season's last ten episodes (after January 8).

In 1990, CBS aired The Flash (John Wesley Shipp) - a new hour-long drama series - in their 8:30-9:30 p.m. Thursday timeslot. Details as to why may be found here:

https://en.wikipedia.org/wiki/The_Flash_(1990_TV_series)#Broadcast