You can do all 18 in 4 hours great course, worth the money!!
We had a group of 4 and it took about 3.5 hours moving at a good pace
Nominally 4:30, faster in the morning or when not busy slower eg 5ish after 10am if busy and speeds up later after 2. These are weekend times week days can be faster. It all depends on who is playing . The rangers will try to move slower groups and remind them of the timing.
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