Guitar - Ear Training; Intervals?

I started doing intervals about a week ago and im learning perfect 4 and 5th, diminished 5th, major 3rd and minor 3rd. I have an ear training program i bought and i've been learning these sounds in 3 octaves;the most it can go and just ascending. I only get 56-60 percent right. I'm 15 and i do 20 minutes of it a day. I get so frusterated and i keep thinking i wont get better. Does ear training take a while to get better?