Once they're comfortable, the sessions turn from a pairing session to a planning session that doesn't last as long, and with a few 10 minute checkins.
Eventually the person ramps up. You just need management to carve out time for this so you aren't overloaded, and you need to make it clear that the person isn't interrupting you, it is part of your job to help them, even being proactive and asking people if they want an extra pair of eyes for those who don't feel comfortable asking for help when they need it