Some online tools are very handy when trying to schedule rehearsal or production meetings. Below are some examples
http://www.doodle.com allows you to create a poll with some suggested time slots and ask members to vote. It's similar to a facebook messenger poll.
http://calltime.online allows you to ask availability of cast and crew members detailed to every hour. Then you can choose which members you need and it'll show you what time slots are possible. It's very useful for scheduling rehearsal. It's also easy to use on smartphones and can import a list of names from camdram directly.
When to Meet
https://www.when2meet.com/ asks members to put in their availability detailed to every 15 minutes, then you can see which members are available for a given time. It's not very easy to use on smartphones.