not when one has bad shoulder muscles like I do. Then it is STRAIN, not exercise, which needs to be the sort that doesn't affect my shoulders badly.

I thought is was because you were petite? If your shoulder muscles are too weak to change sheets, I strongly recommend that you start doing some training because that is the sort of thing I'd expect to hear from a 70-year old woman. Even my grandmother was changing her own sheets until she was about 85, now the cleaning lady does it. Plus, if you have more muscles you a) will be able to do all sorts of things easily and b) be able to eat more without putting on weight.

Ok so here are all the details.

1. I AM petite, which means that my arms are too short to hold a quilt properly while putting the cover on as described earlier on.
2. It is a strain for my shoulders, so I'd rather avoid it. Some muscle pain you can't solve with excercise when it's chronic
3. I eat as much as I want and still don't put on weight
4. I am not a housewife. I work and then have to do the housework, so is it so horrible to want one less hassle out of my schedule? I believe having one blanket and a top sheet makes it easier. For the same reason, I use a hoover rather than a broom...it's just easier. Same reason why I don't wash my clothes by hand, but use a washing machine. There is a difference between housework and excersise. Housework may be excercise, but it's not fun. Some excercise is fun. I'd rather do my work out outside and have fun rather than spending more time doing housework...

To be fair, she may be a 70-year old woman.

Duvets still have to be cleaned, too.

So do I. So do most people.

It's when you want more than you need that it becomes a problem.

Sorry about the shoulders. One of my wife's arm keeps popping out of the shoulder joint. It was my job to change the big duvet. It's easier this way:

Turn the cover inside out.
Put your arms inside the cover and grab the far two corners.
Grab two corners of the duvet through the cover.
Still holding the duvet, shake your arms to put the cover over the duvet.

My mum is tiny and she still manages, you just shake the duvet until the cover has slid as far as possible, then grab on to the corners of the side still hanging out and pull the corners of the cover up, hold them together and shake again. Stand on bed if necessary.
If you have chronic shoulder pain, see a physio, it CAN be solved and I know that because I used to have it too. Like I said, it starts with not being able to put on sheets but will only get worse with age, so do something about it. If you genuinely have such bad problems you should definitely not ignore it and explain to your partner that you need his help (I find this works better than "can YOU please do this or that").
Now you are just showing off Joking aside - lucky you!
I am not a housewife either and I hate housework too. But, if there is something unpleasant I HAVE to do, then I try and change my mindset towards it. For instance, I listen to podcasts while I do housework, that way I am entertained while doing something boring. Changing sheets takes me two minutes tops, so I really don't understand what all the fuss is about.

Ok, as you're just asking which people prefer....
I like the one large duvet system on a double bed as I suffer from cold feet and the small of hubby's back is the perfect place to warm them. Not easy to do if you've got two smaller duvets on the bed.
We have tried the two smaller duvets system but both of us got fed-up with running out of covering in the middle of the night.
Also use a top sheet (between us and the duvet) so that if we're hot we can kick off the duvet but retain a lighter layer between us and the big, bad world.
When I change the bedding (I change the duvet covers along with everything else, I just hang things up to dry and replace. NO ironing involved), I do everything except the duvet cover.... convieniently forgetting to put it back on until bedtime. As he tends to go upstairs first he has to do it or he can't get into bed!

as for preference, I like one big duvet. It has to be really massive though, quite a bit bigger than the bed, so there is room to hog. Yes, changing the cover is a joint effort, but this is something I'm used to, so I don't see it as a big deal. I just strip the bed in the morning and well, we have to put something there before bedtime, so no chance to postpone it really.