50 mg isn't a waste. The gains are just going to be less than..
I've run Halo a couple times now and I don't think 100mg is balls out. I think 100mg is the sweet spot for gains before you start seeing increased sides. There have been plenty of 1st timers using 100 for the entire cycle and they were fine.
My first cyce of Halo was something like 50/50/75/75/100/100 (not quite 2 weeks before I switched to 75). My best gains were at 100 for sure. The only sides I had were slight lethargy for a couple days in the first week while I was getting used to the compound, increased BP (which is manageable), and some crazy back pumps in the second half of the cycle. FYI, I ran no 'Test base' and my energy, mood, aggression and libido were sky-high. I felt great on cycle. I also had no Taurine at the time so the back pumps could have been seriously lessened.
At the end of the day though, you have to do what you are most comfortable with.