I have had success with doing either. I used to do 10% weekly, now I do about 10-15% biweekly (I also dose, I would say if you don't dose and have a moderate usage of cal/alk stick to a weekly change).
Yeah, you can't wrong either way...it all comes down to what's more easier/convenient for you. I personally like the smaller/once a week (10%) water changes better.
yea really its what ever works for u every tank is different coral load fish load diff equipment etc not one tank runs the same . i do 15g every twoish weeks i dont write down so i guesstamate any way have all sps in 75 gallon and all doing great . but like i said differnt tanks need different care lps and softies u can do even less and they be ok smaller bioloads same thing differnt size tanks also make difference smaller usually once a week is good idea bigger the less is needed usually . so pick what works for u and stick with it id say