I have left my birds a few times over the years for a week each when I took two trips to Germany for the Meisterschaft German Roller shows and a couple of times for two weeks each when I did visiting professorships in Granada at St. George University.
The thing I found that worked best for me is a two person system with different responsibilities given to each but both responsible for checking on feed and water and health issues such as looking for hanging droppings and removing any found.
Person number one, Sarah, has been helping in the aviary three or four times a week for about 1 1/2 years. Each time she comes she feeds and waters and cleans cages and sweeps the aviary (it is my responsible on her off days). Each time she comes she is quizzed on how the birds look and if there are any problems she is shown and responsible with me for treatment. I have made a point to discuss treatment options and shared the results etc. She has never had birds and no experience with canaries before I hired her. She does a very good job but occasionally a water is misplaced so it is inconvenient for the birds or a cage missed with feed but with seventy cages which on a couple of days a week she does fast in less than one hour, she could make a costly mistake. Unusual but I always check.
Person number two, Sandy, is my oldest daughter. She has taken care of the birds in the past and she did raise canaries for about a year but gave them up for chickens. She will come daily and do my usual job. Her son and my grandson seems to have gotten into chickens. When John was four he had been to my house when the adults were visiting about the importance of learning a foreign language, as I drove him home he said "Granny, I can speak a foreign language"! So I inquired "what language do you speak"? He said "I speak chicken" and proceeded to imitate their sound! I nearly had to stop the car, cause I was laughing so hard.
John (age 8, plays banjo) says, "I am a chicken who plucks, not clucks!"
Some cages have multiple millet sprays pulled through the side wire.
Click on each photo: notice especially the fantastic tight feathered bottom German roller.