Hawaii Five-0 aired on Fridays, between September and November 1975 (Season 8), but ratings were low due to competition from other popular shows that aired at the same time. Jack and CBS discussed the problem and decided to move the air day to Thursdays. There, it aired from December 1975 until November 1979, with much better results.
Interestingly, the first series episode, "Full Fathom Five," aired on a Friday, September 26, 1968, with very good results.
For many years in Germany Friday night was t h e night to see the weekend in. Five-0, Streets of S.F. whatever aired on Friday night at 9.00.