What is a good feeding schedule for my parakeet?

  My parakeet is a very slow eater and she her food sometimes lasts for a while, but I never know when to change it out. Due to my busy schedule I sometimes leave her for weeks and I don't ever find the time to check it . I don't want to neglect her in any way. How often should I check her food and water?
Feed her a full bowl at a particular time on one day. Then check the bowl the same time the next day - throw out what's left, clean it and refill it with new food.

Any longer, and bad stuff could be growing on the food.

Same deal with water.

Best of luck.
THis may not necessarily be an answer but as an example, I replace the water and blow the empty shells off their food every night. Also, if they happen to have any fruit or veggies, i take them out too, because they'll rot if left in for too long. If you literally check it on a weekly basis, thats wayyyyyyy to long. Mine will only eat theyre seed until the seed shells cover up their food, so even though there is good food in their cage, they will only dig so far for it before they give up (I have 4 so they sometimes i have to do this twice a day). If you desperately need to wait weeks, and i dont recommend you do it often , id say make sure they have PLENTY of treats that will not go bad and switch to gravity fed waterers and feeders, so that they can always get to their food.
What are you thinking? You should never leave a pet bird for weeks without any supervision. Water bowls can be tipped over. Food can be spilled and pooped on. Any fresh fruits or veggies would be rotted. The cage, perches, toys, etc .. will be covered in feces. This is irresponsible bird ownership . If you don't have time for your bird, then I highly recommend giving it to someone who wants it. There are plenty of good people out there who would take more of an interest and care for your parakeet properly. Shape up and start giving your parakeet the care and attention it deserves or give it up.