Can I make M1 schedule exactly 60 minutes' content in the hour?
Yes, this can be done with Version 6, but it is seldom necessary or wise. To do it, you add one of the special "fit to time" units to a clock. This can be either a song or a non-music unit. Usually it would be a song. But I really don't advise using this function unless absolutely necessary because you then have M1 scheduling a song with the Length as the primary attribute. Your other, more important attributes will be secondary. You could get really lousy segues, too may slow/or/fast songs in a row, some of the shorter songs in the library would begin getting many more spins than they would naturally, etc., as M1 is directed to find and schedule ONLY a song that is the needed length to fill the individual hours. While it is possible to get M1 to give a log file that contains exactly a given amount of content time in each hour, it is most impractical....and even if M1 did produce an hour that had exactly 59:59 content, it still wouldn't be right because your automation system has cross-fades built in. If a song is entered into M1 as 3:30 in length and the playout system is set to do a 1.5 second cross fade at the beginning and end of the song, then in actuality the song would get 3:27 seconds of airtime. Multiply that times a dozen or more songs an hour and the 59:59 that M1 scheduled becomes 59:02 or some-such in real broadcast time as the automation system does it's cross-fading.
Almost everybody in radio over-schedules their hours a bit, this so they'll have some extra song for padding at the end of the hour in case it is needed. The other non-music content in each hour always fluctuates. the 10am hour on Monday might have 9 minutes of commercials, the 10am hour on Friday might have 13 minutes. And the hour's will fluctuate with the normal, natural run of songs. 13 songs in one hour may total 59:20....13 songs in the next hour might run 61:02, etc. Because of this, most commercial broadcast stations schedule an extra song every hour than can be dropped if the hour runs long. This need is greatly reduced if you get M1 to import the commercial schedule, then you can click through the finished log before you finalize it each day and clearly see the hours that are over 60 minutes and the ones that are short, then make adjustments before finishing and saving each new log file.
If you need to hit the post and get a Station ID to play at exactly :00 or to join a network at exactly the top of the hour, you can enter one of the Time Update or Sync commands (in the format needed by your automation system), put that unit on a format clock at the end of the hour, and enter the needed "nominal" time on the Clock Item properties.