4 Stands is ok
Had a friend actually ask me about what i did under the car and something she said made me think about stands, hence why my preferred method myself is ramps on two wheels and stands for the front or vice versa.
In southwest Sydney and we had a earthquake not long ago and thinking about it, would the stands have been enough or would it have come crashing down, or what if one failed, would all then move off the stands and fall down.
Or what if someone tripped on a tool and their full weight went straight into the raised vehicle on the stands.
So decided to use my ramps more as they handle 750kg per side and also steady and now setup in a way where i can easily deploy them if needed.
For me, a combo of ramps and stands and even a jack if needed.
Using stands even on 1 end can be fraught with the potential of them coming down on you, even with the ways you have mentioned. Unfortunately, there is no absolute 100% guaranteed way to have 4 wheels of a car off the deck and not have the potential risk of a car coming down on you.....There is always the "idiot" factor that can't be accounted for, or the failure of equipment.
I will add, in no way am I saying you're an idiot.....By the idiot factor, I am referring to leaving tools out where someone can trip on them, or a person that leans on a car whilst it is up in the air, or even with a car on the hoist, the catch not being released properly because some idiot is too busy gas bagging causing the car to tip off the hoist onto some unsuspecting by stander.
The equipment failure can range from a stand breaking to a hoist cable breaking, allowing the car coming crashing to the ground...
So all we can do is, weigh up the options put forward as suitable methods and pick the option we feel safe using.