It depends. Ascension materials to upgrade your 3* heroes will be not a problem if you’ve been playing for a while. The ones for 4* and 5* heroes don’t make their appearance as often and are more difficult to obtain.
Just as @Wad said this is a game of patience or investing money. But even with investing a lot of money it is unavoidable to remain patient.
The higher the level of the titan you’re fighting against, the higher your chances on better loot drops are. Also, the higher your individual damage dealt on a titan, the higher your chances on better loot drops are. I don’t know if anything is applied to the titan chest itself. Of course, it is all still random and you need to be lucky. These things are also discussed in threads concerning titan loot, you might want to read it. For example: Resume of how Titan loot works – Tiers, Scores, theories
However, I am convinced that if you play the game at the highest possible level you’re able to, you will get your necessary materials sooner in general. I wish you the best of luck and lots of joy! 