When I omit a positive control, a trouble comes

I sometimes omit performing a positive control experiment because of several reasons including to avoid much working, and particularly in such case, I have experienced many kinds of mistake. Whenever I meet such problems, I determine not to conduct an experiment without a positive control. Nevertheless, I have repeated the same failures during my research history. I know that I should execute the best way, however hard it is, however long it takes time. But then, please think that you have 16 samples whereas you can treat only 15 samples at one trial. In that case, people will omit using one sample, which is sometimes a positive control, unless it is a very novel experiment. Goddess may gaze me when I omit performing the best, but troublesome experiment, and then Goddess may punish me in that case.