Agree with everything you wrote other than the clarity of the "Every XX hours starting YY minutes after the hour". It was not the least bit clear, at least to me, that I kept seeing 7:00 AM and 7:00 PM because it is based on UTC shifted for local time zones! This is not intuitive!
Yeah, I get that.
All he had to do was offer the option it bit better:
Every x hours, staring at y hour, at z minutes after the hour.
The y would be a single number, identifying the starting hour (with AM/PM if you use a 12 hour clock). I would suspect that any hour specified would be in respect of the local time zone; that does seem to be his convention.