In summer, I do 50% water changes weekly, siphoning out into 20L buckets (which go on the garden) then I fill up with the garden hose - no dechlorinator - I don't add anything. The water temp drops from 27 down to 23 but rises back to 27 within an hour or so. I use to be fussy with water changes, adding stress zyme and getting the water temp just right, but I have found all this extra effort to be unnecessary. Lugging 20L buckets of water around gets tedious quickly!
Winter is a different story as the water temp out of the tap or hose is a few degrees colder. Because of this, I reduce my water changes to around 30% and increase their frequency.
Oh, by the way, I keep africans and they are known to be hardy especially with temp changes so maybe not recommended on other fish families/species and I have yet to have a disease or stress related death.