I started meditating 9 years ago and do yoga once a week and am pretty sure that if I made a lifestyle out of it i could reduce sleep need however I suspect the hours of sleep I gain will be used to meditate so in the end you don't gain that much in terms of free time per day.
You might be more productive per minute after meditating but that's another discussion
I do agree with you, whenever I meditate more often I sleep less. Also, I end up "gaining" time because I pay less attention to distractions/time wasters/procrastination.
However, in my experience it takes years before you may comfortably spend all day meditating. I'm pretty sure most of meditators, teachers or otherwise, are not able to do this. It's extremely demanding, it is only boring if you don't focus properly.
I've participated in retreats that start at 2h30AM and end at 00H00 every day, with 1h sits and 20m breaks in between (same routine over 3-7 weeks), and only a handful of people are able to follow this schedule. Even meditation "only" on a 9-5 schedule is hard.
My original reply was hyperbole. I did not mean they literally meditate all day. I meant that a day in the life of a yogi is very different than that of a normal person let alone a western one so their required sleep time is irrelevant to the discussion