This was a mixed bag for us. We used the purple shuttle and my daughters used the green shuttle. My husband and I hiked the Nevada Falls Loop and the girls did Four Mile Trail to Glacier Point. These trailheads are in opposite directions. The Four Mile Trailhead can only be reached on the Green bus route.
My girls are both in their twenties and my daughters boyfriend accompanied them. On the purple shuttle, we had two bus drivers that were amazing and one of the shuttles was just us and the bus driver. When we were on the bus for the whole loop, he asked where we were going and I replied we just finished hiking and really wanted to just sit in your air conditioning. He laughed and said fine by me. As I said, his bus was empty, Another bus driver was ending her shift and kicked us all off the bus after we sat their for 20 minutes. She said, "Get off and get on the bus behind me". It was green! I went back and told him what she said and he was like don't get on my bus, I'm the 50 minute loop. I was like I know! Another purple bus pulled up behind him and we all made our way to that bus. Actually I thought it was funny but my fellow bus mates had mixed feelings.
Then the girls texted that they would be till about 6 reaching the shuttle stop. So a little after 6, we went down from Curry Village to the bus stop and waited for them. It was almost an hour wait with no bus. Turns out they reduce the (green) valley bus loop to two buses after 5! I know cause I asked the lady on the purple bus and she gave me tons of info before pulling out. (Thanks by the way!) They pulled in about 10 minutes after I finished talking to her. We were hungry at that point, thank goodness the Pizza deck was still open. So just an FYI, bus service is reduced after 5 so your wait will be longer.