Board Thread:Naruto Discussions/@comment-9782468-20170118003542/@comment-31143590-20170125105544

"The user's chakra is evenly distributed among every clone, giving each clone an equal fraction of the user's overall power" (Quote from the Shadow Clone Technique page). Shadow clones will always have a fraction of the original's chakra, no matter how much time has passed. So for example, if Naruto makes 4 clones, each will have 20% of his natural chakra reserves as their maximum, including the original Naruto. The only reason Naruto used the clones for his fight against Pain was because he wouldn't have time to stop moving to gather more natural energy. The only purpose of the clones was to replace what Fukasaku and Shima were meant to do.