Clearblue Digital OPK Question

Megan
Hi Ladies! This month we switched from using the Target brand strips to the Clearblue Digital OPK. I have had flashing smiley faces for 4 days in a row, but now I'm out of tests. Should I go buy more or just use the cheap strips? Also, has anyone else had more than 2 days of flashing smiley faces before ovulating?