Leaving a tip for the maid is a very nice gesture. when I managed a villa on the island. some guests left nothing, it was usually the guests that were the most needy. most guests left 50 euros for the week regardless of bedrooms used. some left 100 euros even if they only used one bedroom. However we only used maid service every other day at this villa, not every day.
The maids that are on the island who work for the individual villas have to pay for their own health care, the owners pay the maids between 18 to 20 euros per hour. most of the time the maids are in and out of the villa quickly, approx around 2 hours per visit. then they go to a different villa to work. this ea ats up lot of travel time for them.
So please tip the maids, they work hard for you and make sure your vacation is a great one!