Yes, definitely for the right person.
Here are average paces in minutes per mile of my training weeks before a 2:54 marathon, done with no marathon specific training. I was 43, and it was my first marathon. I was pretty fast when I was young though (should have been a sub-30 10,000 runner based on 6 mile tempo runs under 30 minutes, but didn't race at my best because I wasn't on a college team). This is running/jogging on trails and in the mountains, with a crap ton of climbing, that's why it seems like walking speed. Way slower than 8:00 to 9:30 per mile:
marathon week: 10:42 pace, including the marathon
week before: 14:14 pace
week before that: 11:19 pace
week before that: 9:35 pace
week before that 11:09
week before that: 10:36
week before that: 10:34
week before that: 12:36
week before that: 11:17
week before that: 10:36
week before that: 10:55
week before that: 10:22