About a minute if I run my little 3 horse barn is down the street and around the corner (its at my grandparents house). And since I kinda feed, hay,water and turnout the horses im there atleast 3 times a day . . . 4 if I ride that day.
Same her I'm about 15 minutes away by car from my horse but I'm only 14 so I don't get to see him as much in the summer because my mom works all day, so I usually get out two or three times a week, but since I don't see hime as much when I do I make the best of the time I have, so I ride and groom and do some work with trailer loading and he is doing good and staying in shape, so I think as long as you are making and honest effort to see your horse its all worth it.
About 200 feet Home horsekeeping has its downside. You can't go anywhere without finding someone to feed/water them while your gone. Its a 24/7 365 days of the year responsibility when you are the main caregiver.
Just wanted to throw that out there so all you folks who have to drive a ways to see your horses don't feel so bad