Sure you can. I mention Saturday and Sunday because most of my guys take their test cyp shots on Sunday. Therefore the HCG injections pick up the system to help counteract the drop in serum T concentration by the half-life of the cypionate ester. It also gives them a good boost on the two days of the week they most be able to enjoy it.
My analysis of the body's response to HCG tells me doing it two days in a row is best. But doing it on ANY two days of the week is a vast improvement over, say, "cycling" HRT--which is just plain stupid, IMPO.
Some of my Androgel patients take their HCG shots every third day, and that seems to work fine, too.
I now have a few guys who use HCG every day, with a small dose of test cyp each week. This protocol I have, thus far, offered only to the guys who have not responded well to TRT as far as libido is concerned. It does take a little extra fine-tuning for me. But the results are well worth it for my patients.