Recently I have been giving a lot of thought to whether I am spending enough time each day working on [a certain] project. On one hand, I am working on it at least 30 minutes a day/5 days a week. However, on the other hand, if this project is one of the reasons Hashem put me on the earth, then 30 minutes is certainly not enough.
I don't know know if there's any connection between the thoughts that if something is one of the reasons one is created that one necessarily has to spend more than half an hour a day on that thing. Is it ratzon Hashem for you to spend more than 1/2 an hour a day on it? Well that would depend. What are the alternatives? If you did spend more time, would you not have enough time to be ma'avir sedra or to learn Gemara or halacha or whatever your other sedorim are? If spending more time on it would mean doing something that you have reason to believe is against ratzon Hashem, then that would imply that spending "only" 1/2 an hour a day on your project is ratzon Hashem.
And also, what do you mean by saying that the project is "one of the reasons why Hashem put you on earth?" If you mean that on its literal level (that it is one of many reasons why Hashem created you), then what about the example of politely smiling and thanking the check-out person at the grocery store? If it's ratzon Hashem for you to do that at the moment you finish your transaction with her, then that too is "one of the reasons Hashem put you on earth." Does that mean that you should davka spend more than 1/2 an hour smiling at check out girls? Obviously not.
Everything that it is ratzon Hashem for one to do at any given moment is "one" of the reasons why Hashem created him. But the amount of time one should spend on that thing depends on what ratzon Hashem says is the appropriate amount of time to be spent on that thing. For pleasantly thanking check out clerks, that's probably about 1 second. For learning kitzur shulchan aruch yomi, it's probably the amount of time it takes to learn that, let's say 10 minutes.
For your project, my personal opinion on how to "divine" what the amount of time is that Hashem wants you to spend on it is: See how much time you have after all of the other things you have to do. And then ask yourself where you would get the time from if you increased how much time you spent on it. (e.g., some other learning seder, sleep time, family time, work time...) Then ask yourself whether, in the aggregate, you'd be failing to fulfill what Hashem wants of you in those other areas of life. If so, then perhaps 1/2 an hour a day *is* what Hashem wants from you. If not, then you know you should increase the time since it sounds like you feel a pull to increase the time.
Make any sense?