do you really need a new app?

today, there are many many apps you can download on your laptop, smart phone or iPad. many of these apps could promise you a complete comfort or solving annoying problems, or just to make your life much easier. Most of these promising apps come with a high price tag, others could be free…but the main question remains: which one i do need and which one will really solve my problem?
as a phd students trying to seek any help while writing my dissertation, trying to purchase some of these apps….do i really use them? not really.
I bought organizing apps, i bought an app to help me writing, i download more organizing apps and more helping apps in writing, and so forth. you got the idea. and which one i really use? none. why? for different reasons, but i believe if they really are helping me and bridging a gap, i would not give up on them. most of them are hard to figure and i have no time to go back to the manual each time i want to figure out some, which means it has an usability issue. so i end up with more complicated problems.
in this time where everyone is in rush, and you need your materials to be ready yesterday, there is no time to lose learning a new app that should make your life easier, especially if it costs you $$$, and you are only a student counting each cent.
but what do you think? it would be great to read your experience regarding apps, please feel free to add your two cents here.