Keviat Etim L'Torah
Fixing times for Torah Study
Torah study is important in Judaism. Judaism tells us how important more by describing the way in which it needs to be a regular part of our lives than by expanding on the spiritual and metaphysical benefits of Torah study (though it certainly does that, too).
The halachah is that we should each fix regular times for Torah study, morning and evening; whether times short or long; whether in a class or with a learning partner or alone; whether studying Talmud or halachah or Jewish thought.
All these variables depend on a person's time, interest and ability; but they are less important than that we fix a time and stick to it (Maimonides Hilchot Talmud Torah, 1:8).
Even if you stand to make a lot of money by cancelling a fixed learning time and doing business instead (say you see on your iPhone there's a sudden spike in currency futures and you feel that you have to sell now, right when your learning partner walks in), the halachah says that you should keep your regular learning time, and believe that the money will come back to you in some other way (Shulchan Aruch, Orach Chaim 15 2:1).
It's more important to have your priorities in life straight.