i have 3 9-10 week old anconas.
the initial set up i had for them was too small, so when they moved from the brooder they moved in to the chicken coop. i had just finished winterizing & the chickens were on lockdown. they were 15 weeks at the time.
the chickens were not what i would call "welcoming". they tried often to break through the barrier i had separating the duck area from the chicken area. (OFTEN = constantly.)
i gave it 48 hours, just to see if they would sort it out.
i cleaned the coop everyday but it was not a maintenance cleaning, like i do everyday with one clean out a week. everything was soaked, the whole coop smelled like duck. everything had to be cleaned & washed & all the bedding changed everyday they were in there. i started to think i couldn't handle the ducks, they were just too messy. (i had read A LOT & "knew" that, but reality was much worse for those 4 days than i had anticipated.)
after 4 days i finished the remodel of the duck enclosure. the ducklings (4 weeks old) had enough to deal with being in their adolescent phase & petrified of everything as it was.
the chickens still give the ducks a hard time. they are like a gang. they roll deep up to the duck yard, and if they can - while i am cleaning the enclosure, etc - they parade around in there, showing the ducks who is boss.
sometimes i feel like i am watching the crips & bloods.
the chickens don't really do anything to the ducks. they don't peck or attack them. but they do broadcast their strength.
i have 2 more anconas that are about a week away from being old enough to join the others outside, and i hope it makes the chickens a little nervous, 5 ducks, rather than 3. they will be almost evenly matched.
for myself, i would not go back to a shared space. even though all had the "correct" number of square feet, it wasn't workable for me. now that the duck enclosure is up & almost complete (maybe, are they ever done? i want to make little modifications to both the coops all the time.) my clean up is SO much easier. the duck enclosure is actually much easier than the coop, and only takes me about 15 minutes a day, if i don't stare at the ducks the whole time. (which i do, and am out there for hours.) when i do my "full" clean out - weekly - it still only takes about 25 minutes, which is less than the 35-45 minutes the chicken coop takes. when they shared it was about an hour of clean up a day. also, the ducks are much happier not in with chickens. they are fine in the common areas of the yard together, which is nice. i am sure if i got them all at the same time it would be much easier for them all to play nice & be friends, but anconas are so hard to find out here & i had my heart set on them as my first duck & was not about to "settle". i am glad for that, too, as i find them endlessly fascinating.