Flexibility is key
You have meeting (or camp or event) planned out to the minute but nothing seems to go as you planned...
Yes this will happen often. You will learn to be flexible, to consider all plans tentative, or you will go crazy. Children's preferences are not always predictable, and the weather is often a disruptive factor to your outdoor plans.
Always have back up plans, if you don't have them, you WILL need them.
Have game and time filler ideas ready for those moments that arise.
Have color sheets or game sheets or some activity to occupy them at the beginning of meeting in case you need to talk to a parent or delay for a few minutes.
If you have an activity planned for meeting and the girls just do not like it, change it!
If you have planned an overnight and everything gets off schedule, so what, are they having fun? Then its all good.
If you have this big outing planned and only 3 out of 10 show up, go on and do it. Make it as fun as you can make it for those 3 girls. They will go back to meeting and talk about all the fun and next time I bet more show up.
Girl led factor...the girls want to have a meeting with snacks and chatting. "Okay lets do it, this could be the meeting right after we finish _________ (journey, badge, etc)."
You can stress yourself out over little bumps in the road, it's not worth it...