During 6 days, Laura would spend 2 * 6 = <<2*6=12>>12 hours in the park.
If it takes 30 minutes (or 0.5 of an hour) walking to and from the park, then for the six trips, it would take her an additional 0.5 * 6 = <<0.5*6=3>>3 hours to walk to and from the park.
In total, she would spend a total of 12 + 3 = <<12+3=15>>15 hours on her six trips.
So, the fraction of time spent in the park would be 12 / 15 = <<12/15=0.8>>0.8.
Thus, converting fraction to percentage, Laura spent 0.8 * 100% = 80% of her trip time at the park.
#### 80