For some situations pair programming is not effective. Be prepared to allow yourself and your team members to have some time alone.
Motivation
Even though we love pair programming, we can't expect anyone to constantly think out loud. When some seriously deep thinking needs to happen, or you just need to fiddle with something to find the right questions to ask; pair programming can block you. For these situations and just to keep the joy of solving a puzzle in isolation in the work alone time is great.
Applicability
Any work on a problem that is not resulting in production code might be a candidate for some alone time. In particular when you get into a situation as a pair that you're both looking at the other for ideas it might be time to split up, scour the internet fret with some ideas and reconvene when you've found some clues. Doing nothing is also a very important part of creative work. Alone time might be needed even if there is no work that deserves being done by someone on their own.
Application
Timebox alone time. Make a date with a pair buddy before you go off on what might very well be a wild goose chase. Then when the timebox is over assess the situation with someone else. The harder the problem is, the harder it will be initially to get somewhere. Sometimes great ideas come to you while you're ironing your shirt or making a sandwich. Sometimes staring out of a window for a couple of hours is the most productive thing you can do. Setting up rules for how people should spend alone time defeats the purpose.
Consequences
Enforced pairing should not be for 100% of the time. Alone time gives the brain time to recharge and ideas time to react with each other. All production code should be written in pairs. It follows that we must not plan people to work in pairs on production code 40 hours a week. 100% efficiency is unhealthy in creative teams.