Rehearsals for a production are a serious business. In the very least they should be to you. A lot of energy, and eventually, money, is invested in a community production. Wasting time dedicated to making a show a success indicates a serious disrespect for the theatre, and your fellow cast members and crew, not to mention your future audiences. This doesn't mean you should never have fun while rehearsing. It’s not the army, after all, but there should be discipline, and a willingness to get down to business right away.
Unless you gather with a few people you share scenes with, and rehearse informally.
Schedules can be a tricky business to navigate, but if you can manage it, take time outside of rehearsal to meet with your cast mates and go over the scenes you share. Even if you only have one such opportunity, take it. If nobody has suggested it, take the initiative yourself and suggest a time and place to go over your scenes. It is preferable to work on all of them, but for certain at least go over your longest or most problematic moments together.
Gathering outside of rehearsal accomplishes several things. To begin with, it gives you a chance to become comfortable with cast members you have not worked with or met before. Meeting for a read through at a coffee shop, or at a local park if the weather is warm can begin to tear down the awkwardness that often exists when people first begin working together on stage. And while this is not an absolute necessity in order to perform well together, it certainly does no harm, and when done early in the official rehearsal process, it more often than not will increase the productivity of regular rehearsals. Being “warm” to one another right off the bat eliminates the need to get used to one another during early official rehearsals, and hence leaves more time for developing the characters and the scene.
The benefits of these informal get-togethers are not limited to those who have never worked together before, however. Regardless of how familiar you are with your cast mates, an informal reading of the scene outside of rehearsal allows for more casual and open communication. This is fertile ground for new ideas and approaches, both to character and to the scene as a whole. Digressions, experiments, and questions for which there are little time during rehearsal can be given as much time as the group decides they are worth when the setting is social.
Finally, though it should be obvious, I will mention that a huge benefit to these meetings is that they are, or at least should be, fun.
You will meet those in community theatre who insist that it is in bad form to meet and run lines or discuss the play without the director being present. Such people consider it a cardinal sin to try to be creative without permission.
Ignore such people. While it is true that a director must provide vision to a production, only a poor, or power hungry individual will have a problem with some informal practice and brainstorming. Which, of course, is exactly what it is; brainstorming. It is not making a final decision, or overturning a direct instruction. It is exploration. It is getting comfortable and creative. It is enhancing the enjoyment of being in live theatre. Any actor or director that would deprive you of such things is probably not worth working with anyway.