Summer (1stmay to 1st nov) as much as we want......
Winter abou 12 hours max, in the snow about 5 hours and if it's torrentual rain for weeks on end we have restricted to about and hour aday or if needed kept in for a week or two to rest feilds.....but the school, lunge pen are in with livery and we have miles of both off road and road hacking.
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Summer in for about six hours from ten am
Winter out at some point during day for about four hours Out about seven if on a non work day.
Some fiddling around spring and autumn during charge over time .
Never ever in the field for a full 24 hours .
Another vote for as much as possible . . . he goes out even if it's snowing - but not for long as the ice balls up in his feet. Goes out in all other weather too . . . even if it's just for an hour or two (he does have a tendency to be a bit of a nutcase when it's miserable).
So . . . in the winter he goes out from about 8 until about 3 . . . in the summer he stays out longer - 'til about 5'ish.
Mine are out 24/7 whenever the field isn't trashed by them being out. If it's dry or snowy or frozen, they're out. Current sea of mud means they're only out for about 8 hours a day, but that's only been for a couple of weeks (and it's got to dry up soon, right?)
Depends on the weather rather than the calendar date, and whatever management regime they need, though a rule of thumb would be daylight hours all year round minus their working time - they are ridden most mornings. Not yet had one that didn't like to come in for part of the time - some of the supposedly 'hardier' breeds we've had over the years have been the keenest to have 'stable time' (and lots of it!).
Not to everyone's taste I know, but it works for us, and our microclimate and facilities.