I think so! Now it would depend when you are going but I think for most - you could cover DL in two days and DCA in one. Make a list of must do's so you have a small plan and then go have fun and enjoy DL and DCA.
I went to Disneyland in February, and we only had a day and a half to do both parks. Actually, it worked out well; we went to California Adventure on a Thursday evening and saw EVERYTHING in three hours (this included a sit down dinner!). We did Disneyland in a full day, and while we had to skip some of the attractions, we got done everything we wanted to get done. I believe you will have plenty of time to see everything in three days.
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