It is easy to understand, imagine/predict or even conclude.
Madara is not going to fight every single shinobi at the battlefield... Even although He may have really huge reserves of chakra surprassing even Hashirama himself... He could fight two days non-stop...
But against him they are powerhouses as well: Naruto, Hashirama, Tobirama, BM Minato, Sasuke combined with Orochimaru, Hirzuen and possible evert shinobi at the battlefield... Madara is greatly outclassed... outnumbered.
His greatest chance is bring havoc and chaos to the battlefield by using very powerfull destructive techniques but as little as it is necessary to force his way towards Obito... to get Gedo mazou out of him and then do something with God Tree... absorbing tailed beasts or eating forbidden fruit.
It could be enough if he can use full potential of Rinnegan to kill them.. but if not then even knocking out the most relevant powerhouses in SA could be good plan to go after his aim...
Either way Madara need Forbidden fruit or becoming Ten tails host to last long enough and be final threat which can really put entire Alliance in danger... He better not play around and fool or he can be dead in no time.
Also The moment he is aware that he is alive and can be killed is the moment since which Madara can fight completly differently in compare to what we have seen.
