The story seems to indicate it was a long standing war with periods of intense action followed by short or sometimes long periods of light skirmishes.
The forces fo the 5 nations would more then likekly not throw massed waves at each other every battle but engage in a long series of skirmished with a few nasty big battles over strategic elements thrown in.
Actually they messed up on several details, including one really major one with the chronology. The soon to be Sanin faced off against Hanzo during the Second Ninja war not the Third. Second Great Ninja War happened from when Nawaki died to around the time Jiraiya returned from training Yahiko, Nagato and Konan. (roughly from when the Sanin were 16-21) Kushina's birth country was probably destroyed right around the end of that war and she became a refugee child in Konoha. Jiraiya would have become the Jonin sensei to Minato and his team mates right around his return. (In the manga he even says to Nagato, Yahiko and Konan the war looks to be ending very soon- not "before you are grown".)
the Third Great Ninja War probably started right around the time Dan died, when the Sanin were right around 27 and lasted until they were 37. With the messed up chronology the episode gives Minato would been born around the same time as Kakashi. Ugh.
They also messed up on Hanzo's eyes and Konan's eyes, and the colors of Kushina's dress- in the manga Kushina's shirt part is obviously lighter than the dress part- they messed up and made the shirt darker.
Also another boo-boo character wise, Tsunade's mocking of Jiraiya- saying if she dated anyone she'd chose Orochimaru over Jiraiya- no, she disliked Orochimaru even more than she did Jiraiya- she says right inn the manga that she never liked or trusted Orochimaru. She may have actively disliked Jiraiya when they were young, but she clearly always trusted Jiraiya and despite her irritation at his acting like an ass and a pervert she much perfered his company to Orochimaru's.
That being said I actually liked these episode a lot (which made the problems I listed so frustrating! The chronology mistake especially was inexcusable) Jiraiya's character growth and Jiraiya and Tsunade's interactions from mid teens onward were fantastic. I had to laugh at the filler with Jiraiya's "Captain Oblivious" moment- Tsunade makes a very obvious leading comment about "settling down" in Konoha and Jiraiya totally misses it and talks about his destiny instead. This is even more oblivious than Naruto missing Sakura's flirting and accidentally saying something unintentionally insulting. Jiraiya was older and that was a really obvious suggestion that she was interested in being with him. Jiraiya just continued to cluelessly make the wrong (insulting then a perverted come on) approach, instead of noticing how she'd get interested when he showed his serious, determined side. He finally did notice that during their conversation before he heads off to Rain country but he still seems uncertain he's seeing what he thinks he is and tells her he's joking- this time she sees through him and knows he actually is in love with her (and she knows she's loved him).
They had some nice filler moments with Jiratsu on both sides that I really enjoyed in these episodes. I would have liked to seen a filler moment showing how he dealt with seeing DanxTsunade and what his reaction was when Dan was killed. I wish they would have also given us a filler moment showing Jiraiya with Minato and his team mates and young tomboy Kushina driving him crazy with her hanging about fighting with the boys and constantly talking.
Dream you dream alone is only a dream, but dream we dream together is reality- Yoko Ono 1971
When you go to war, both sides lose totally- Yoko Ono
Remember, our hearts are one. Even when we are at war with each other, our hearts are always beating in unison- Yoko Ono 2009