13426 said:
How long does it take on average for the reviewer to approve an image? Sometimes the uploaded image is approved immediately, but sometimes it is rejected after three days. If it is not approved on the same day, can I understand that the image does not meet the standards?
Approvers aren't paid, they go through the queue when they feel like going through it. Someone who might choose to approve a post may just not check the queue within the three day period. Some approvers go through the queue in reverse (meaning they start from the oldest), so some posts get approved right before they would be deleted automatically. More popular stuff tends to get approved sooner, just due to a greater number of approvers with an interest in it, more niche things may end up deleted if the one approver willing to approve it happens to not be around.
Short answer: It depends on what you're uploading and which approvers check the queue while it's pending.