you can fight for a long preiod of time without fatigue.
To fight for a long time and not become weary is something that requires stamina.Not strong chakra.
Strong chakra means you can use a justu and it will be more powerful then someone who puts in an equal amount who does not have strong chakra.
Or if something usually cost a lot of chakra the person with strong chakra will not have to input the same amount of chakra as someone else.
Sasuke has strong chakra.
Madara is known to have the strongest and most wicked chakra of the entire uchiha clan.
Naruto has a large chakra pool.
Naruto can just keep inputting chakra into his justu to get the job done.