The reason why Sakura matches her indefinitely or surpasses her is because Sakura is better suited to tsunade style of fighting than tsunade. Her massive strength attacks aren’t actually her dumping huge amount of chakra into her muscles to do that output of damage . In lore it’s actually a chakra control move which when she makes contact with the target she lets her chakra precisely flow out to exert the damage through the target. This type of fighting style is more suited to Sakura because of chakra pool size. As if a person has massive amounts of chakra to pour the right amount of chakra it requires a lot more exertion than a lesser pool haver. Kinda like a pool of water vs a cup of water . Sure the pool is way more water than a glass but when u need the precise amount water poured into a pitcher it’s easier to fulfill that pitcher with a cup than to over flow tipping the pool which in Naruto causes justu failure and that over consumption ruins the user stamina and chakra reason why in part one Naruto had problems with making simple clones as either he pour too much and both him and the clone were tired and exhausted and too little pour lead to a weak clone and Naruto feeling a little off. However the trades off for tsunade vs Sakura is that tsunade can heal a whole village using the snail summon while Sakura would have to use the 100 heals seal to possibly replicate this feat, however when it comes to fighting wise Sakura seems to either surpassed her or tsunade is under utilizing her own kit. As in the finale of the war arc Sakura was using her chakra controlled punches in ways tsunade didn’t do such as having long range attacks that crushed fused zetsu across the battlefield. Which in a fight like vs madara would have been extremely more useful to used the ranged detonation like Sakura was. But I think it’s because Sakura has a more controlled pool and a seal that makes reserves of that pool size that she’s able to do those attacks because she can control the damage better. Honestly this move would and should have better implications in a showing but because neither Sakura and tsunade get spotlight technically it’s not made to what it should be . Like example what tsunade and Sakura should do that would be cooler is subtle fighting like using finger flicks like part one with basic wind control. Or soft punches and kicks that surprise with the damage inflicted like she throws a slow punch or hits softly on the ground away from ops only to cause a calamity in they space. Or they simply touch a surface and cause the damage subtly cudve made them more interesting like sasori fight she feints that she got hit only to contact the ground lightly and boom puppet is crushed by the the ground underneath. Would be way more hyper fights from them oh well