We found that a lot of rides were fine with 3 people across but I'm a small adult. We're a family of 5 but had the three of the kids under 7 years old on couple trips. Since then, we have had our eldest go without an adult before, and that hasn't been a huge issue. They always put him in a row that was in front of or behind us. I gave him instructions to meet us near the exit if we get separated but that was never an issue. The only ride that caused us issues was Speedway, as the child needs to be above a certain height to ride without an adult. Even using riderswap, that one would be tricky, as someone needs to wait with those not riding slowing down the trading out.