Yes sir! It's possible to gain that percentage of profit in day trading. It's is the best percentage to gain a nice profit for every trade. Don't try to set higher percentage of gains, if you set your target profit to 2-5% and make another trade with the same target percentage you ca easily gain more profit.
But I doubt on ethereum, if you have monitored the move of ethereum everyday thn probably you will succeed but if not, try to look to other coins that has a high volume on market.

It's up to the market and to your basis on how you analyse the move of every coin.