If you're from the biz and over the age of 30 the above block and razor pic probably looks somewhat familiar. The block is made of hardened aircraft strength aluminum. It's precision machined, and will hold down the tape while cutting and taping. The cut slots are standard at 45 and a 90 degree angles. It was used with splicing tape, which came (at least in my day) more popularly in pre-cut sticky tabs. I've used this bastard. It works. But digital is better. Anyone else ever sped the time to edit out every "um" from a bad interview?
Top-forty radio, back in those pre-niche days, relied on having a variety of music on its playlists. If you don't like [whatever is playing now], don't worry because [whatever the next song is] will be something completely different. But of course that worked much better when "the next song" was only two or three minutes away. The eight-minute album cuts from 1970s AOR got in the way of that angle. Various radio stations handled the situation in different ways.
At WRKO there was "the RKO edict" No song over 3 minutes got on air. It was then PD Paul Drew's solution in 1974. Reputedly it was broken twice within its first three weeks when much-longer-than-three-minute songs by John Denver and Elton John were added to his stations playlists.
Elsewhere these decisions were usually made on a song-by-song basis. Unusually in the format, 99.5 WEFM in Chicago prided themselves on playing the full length versions. But then, WEFM was a unsuccessful Top 40 radio station. They eventually dropped the format in 1980 after only 4 years of watching it succeed almost everywhere else. Some Chicago radio history here: http://radiotimeline.com/95wmet.htm
Particularly problematic was the single "Stairway To Heaven" which came out in in 1975. Stations like WLS did cut out all the instrumental bridges, leaving only the vocal segments trying desperately to make it down to the 3 minute goal line. Incidentally, it sounds like crap when you hack out that much of a song. Massive awkward edits like that are blatant to the listener and have a negative impact.
Today record labels, in an effort to avoid hatchet-jobs like this, issue studio-made radio edits of various lengths. ...and it benefits us all. The radio station plays the song they want, the artist gets to record the song they want, and you get to purchase the version you want. And thankfully no one has to listen to bad versions that no one wants.