The answer is YES. The seasoned theatre-goer will understand, however, that there is a distinct art to making the most of intervals. One must follow the rules, and the choreography – that is: be ready; applaud; leave briskly; toilet; drinks; find a space. The etiquette for each manoeuvre goes something like this:
Be Ready
It is usually fairly obvious when an interval is about to descend. Use the last few minutes of Act One wisely: find the shoes that you so carelessly kicked off earlier; locate your handbag; clear your lap of drinks / sweets / tissues – find somewhere safe for them (by that I mean a place in which they won't be kicked or trodden on). Importantly, make sure that whoever you are with knows the exit plan (see 'Leave Briskly').
Applaud
Leaving the auditorium before applauding is an abominable rejection of Theatre Etiquette. It should be done under no circumstances – it does not matter whether you need the toilet or forgot to pre-order you drinks; there is simply no excuse. Everything else comes metaphorically and literally second; first, applaud.
Note: the same applies to the end of a show. Never leave before applauding.
Leave Briskly
There is a certain art to leaving briskly. You don't want to be stuck behind someone who walks about as quickly as a tortoise with a sprained ankle but, equally, you can't be pushy. The good thing about auditoriums is that the seating allows for numerous exits; a quick assessment of the situation should allow you to ascertain the best exit strategy. If you master the art, you will find yourself happily sauntering up one set of stairs, watching the slow-mover on the set of stairs next to you with a feeling of well-deserved smugness. Once on track, a brisk walk (and no elbowing past people whatsoever) should allow you to get out quickly whilst still adhering to the etiquette. Easy!
Toilet
It if infinitely baffling how, no matter the briskness of your exit, there is always a queue at the toilet before you arrive. This great mystery can leave the victim of queuing feeling frustrated, confused and upset – but try not to be overwhelmed by such emotions. Waiting for the toilet cannot, it would seem, be avoided, so you may as well stop huffing and whining and politely wait for your turn. Again, no pushing please.
Drink
Drinks can often be pre-ordered; if this option is available, take it. By the time you have emerged from the toilets, the bar is likely to be crowded and all but inaccessible. If you have not pre-ordered drinks, the queuing etiquette is here much the same as it is for the toilets. If you have pre-ordered drinks, you are allowed to feel quite smug.
Find A Space
By the time you have gotten this far, you are probably half way through the interval. At this stage, it is worth finding and protecting a space of your own. The foyer / bar will by now be extremely crowded, and spaces are hard to come by. Again, there are certain rules: don't stand too near someone else – invading personal space goes strongly against all rules of etiquette. Similarly, it is not okay to sandwich someone between you are your friends. If you're talking over somebody else, move away. It is likely that, somewhere, there will be a space that you can inhabit, you just have to keep an eye out for moving people. You might be lucky, and a group might move away leaving a whole table free. In which case, it is time to employ the walk-briskly-but-don't-push strategy, and hope that you get there first. At the end of the day, this last stage comes mainly down to luck.
Once the interval is over, it is time to return calmly to your seats, breathe a sigh of relief and enjoy the rest of The Book of Mormon; hopefully you will have achieved all of your interval aims without breaking The Etiquette. If you have, I commend you.
I wish you all the best of luck in your intervals to come!