Tonight my band, No Excuses, is rehearsing for several hours before playing 2 gigs this weekend. I'm a bit nervous about the gig on Sunday, because we have only been rehearsing for Saturday's performance. Since Sunday's is twice as long, we'll no doubt use about 3 hours or so to focus on Sunday's gig before we polish up for tomorrow's. Then I can breath better and sleep well.
If you are about to present a case to a jury, an informational topic to prospects or open an event for your community, it takes practice. This is not a mental review, reading over a script. This is an on-your-feet, outloud rehearsal, complete with movement, projection, eye contact and high energy. In front of others.