Yea makes complete sense. But what if you had bought those shares last September? Would you wait until sept to sell, even though it hit that 7.50 in May?
The time period doesn't matter, but in September, you would have bought in $5 range. So if you have a 50% return, and you're getting nervous, take your original investment out and leave the gains.
FWIW, I have no idea what Sprint stock will do in the next 6 months, 1 year, 5 years, or 10 years. It could go as high as $100/share, or drop as low as $1.00.