Well, yes, the actual money usually comes at a later time, but you can identify the impact of your action right away.
The immediate reward for going to work is you get paid for that work, however usually not right away. At least that's how I see it.
Our points of view might differ. But it's not very important.
A bit more on topic, it is kinda strange that windex would be able to go two full months without an additional ground mission. I usually get so many I think they get tedious. Chris would be able to answer this better, but I don't think what type of alien missions spawn is completely random, in which case this could happen.