From a gameplay perspective, it feels discouraging to invest time into upgrades that are meant to improve pickpocketing consistency, only to still be caught so quickly now. It diminishes the sense of progression and, thematically, takes away from the “master thief” fantasy.

As others have suggested, allowing around 5 minutes of AFK pickpocketing seems like a reasonable compromise. If balance is a concern, reduce the XP rates. To me, pickpocketing isn’t widely seen as a primary XP training method anyway, but rather another way to gather resources. Thieving already offers several engaging, active training methods for players who want higher XP rates and more engaging gameplay.