I'd say yes, it's possible to create a successful side and winning titles without changing to much on your formation. But note that in real life, its few times that play this way. Barcelona play in a similar way almost every game, but they do make changes. These changes might not be a big change like a change from 4-3-3 to 4-4-2, but they still change their approach in regards to the opposition. The main reason why they also play in basically the same shape every game, is that they have a very specific group of players, all bought/produced at La Macia. These players are amazing, but wouldnt necessarily look so good if trying to adapt to a very direct, physical style of play. Probably the main reason why Zlatan didn't succeed was that he did not suit the system. How many times haven't we all experienced that in FM? So frustrating to see a big signing playing to a 6.5 ratio on average, but if they don't fit the system, they will not perform, neither IRL of FM13.
I basically play the same formation every game, but I've changed my go-to system two times over 3 seasons, trying to adapt to my group of players. Fighting for trophies in Europe and the EPL with QPR, but because my budget is small, I can't pick players from the top shelf. I therefore try to buy players to fit my direct, high-tempo style of play, but when I cant get the right players, I might have to compromise on my formation.
What I do change a lot before games is player movement/roles as well as team instructions. I might play with more direct/shorter passes, higher/lower tempo, counter-attacking/controlling etc. This has been successful with my 4-2-3-1 (deep DM's) because it's not a formation that has major gaps in it, it covers a lot of room. If you for example play with a very narrow 4-4-2 diamond and you play against strong teams that has excellent wing play, I'd say you're in big trouble. Basically, it depends on the strength of your team and your players. You always have to adjust to your opposition, but I'd still say that getting the most out of your own players in a technical/tactical way is key! I have wingers that are either really good at counter attacking, possessing great pace, dribbling and finishing, as well as more playmaker-types that can create chances against a defensive side (think Junior Hoilett vs Esteban Granero). This is important elements that you need to take into consideration. If you play with Wigan, you're not going to control many games, and you probably only need one style of play, but if you're up against teams that will just sit back, the same players might find it very hard creating anything!