Always in the school, at least you're contained! Think it feels safer. I wouldn't have the guts to hack out on a brand new horse!
I think it was my boy's first ever time in a school when I trialled him: he trotted on tiptoes all the way round trying to look at himself in the mirrors that were placed for the massive 17hh warmbloods (he's a little 15hh cob!)
I haven't got a school, so always have to hack out. Our lanes are quiet and I'm confident anyway. I think wherever you ride, alone or with company, you need to be quiet and confident, so let that affect your decision.
School or section of field I think, but it depends, if you've ridden the horse a few times already when viewing etc you might feel more confident. I probably wouldn't mind a hack in company but alone might be a bit much.
I've jumped on loads of horses that I haven't ridden before and taken them hunting or exercise for polo. If you work on a yard, that's what you do - jump on and get on with it.
Basically it depends on the horse - has it done the job before? Does it know as much as you do or more? Is it a youngster that needs bringing on carefully?
Its horses for courses - each situation is individual
She's an 8 year old ex polo pony who's been out if work completely for about 6 months. She was the polo yards favourite hack so know she's good to hack but she's still a little on her toes when shes turned out and neighs constantly and jogs and spooks at monsters all over the place.
in the school although I rode in a 4 acre field... not ideal but I didn't have anywhere else but no I wouldn't hack out as I don't know them well enough to know what they are going to do
I don't have a school and most of the time I don't have anyone to ride with. My last two I have ridden up and down the lane and around the field a bit on the first ride to let them see the surroundings. Second ride is time to hack out and go and explore. That is what works for me.