Thank you Sniperdude and Dreadful Cadillac.
One additional note for managing a Team. I encourage teams to work in "cycles" during a round. All 1st place donations are Cycle 1, all 2nd place Cycle 2 and all 3rd place Cycle 3. This is the best way to discourage sniping and allow a team to react to and mitigate the effects of outside donors on the process.
When team members begin to donate at the same time to the same GB they will invariably open up sniper windows and that you don't want. You can never totally eliminate the risk of snipers, but keeping in cycles seems to be the best way to discourage it and mitigate it when it happens. It does require members to be attentive, and to pause their donations on occasion but it is the best practice I think.
Wait until your 2nd place Target Assign's 1st place donation is complete before you begin, and same for 3rd. If your team can be true to this, it will be best overall. Teams can get anxious, complacent and on auto pilot at times and this is when they can begin to donate on top of each other and when this happens they will get sniped. So just keep that in mind if you manage or are a member of a team.