I can end up halfwheeling sometimes. Its mainly when i go up inclines or into a wind. The rider next to me will sometimes drop back slightly.
What i do hate is when you get the rider that comes right on in next to you, when they could sit slightly further out. That sits in the middle of the 2 people infront so your either behind them or at the side in the open.
Also dont like it when someone isnt that fluent. I'm probably not hugely fluent but when the person infront goes then slows down, then goes, or freewheels so you have to just brake slightly.
JohnG, if you started as a group and train as a group, if someone punctures then they should stop, and at least offer to help do something like get the spare tube ready, pump off your bike or tyre levers. What ever time is lost there can be made up by working slightly harder later on.