Learned a new G+ tip the other day and I thought I would share. If you are refreshing looking for a better time on a single ride... Don't pull down to refresh then click the ride once you see a better time come up. Often times you will be too slow and someone else will have gotten that better time.
Instead of refreshing that main page, simply click the ride on whatever time it does to move on to the confirmation screen. The time will automatically shift to the latest time available (which might be different that the tip board screen). If it is not the time you want, click back and do it again. This way if you see a time, you are holding that time as soon as you see it.