If I change the value of a code variable of a variation while an experiment is running, how soon does it come into effect? Anything I should consider?

While we don’t advise this course of action while an experiment is running, what would happen is that it would change for everyone. However, it may take 15 minutes to clear any caches and it won't change until the next session.

A session defined by Taplytics is whenever someone backgrounds their app. When a user re-opens the app after that session, the new value for the code variable will take hold.