I did the same thing for a while but I stopped recently because HIVE and HBD are too unpredictable with pumps every now and then. As you said you don't always earn a profit and sometimes you have to take a loss.
Also, there are days where you may earn only 0.1 HIVE extra versus days at 300+ profit.
A couple of month ago, I had a really good week. I started with about 500 HIVEs and finished the week at about 1100 HIVE. But then the next week, I took a loss of about 300 HIVE. You win some, you lose some...