You learn to trade on simulations first, margin comes last. Actually should never come into play, cuz this way , ones is giving the wheel of his life into someone else's hands.
The mystery has been solved. For most of the names I trade, IB happens to have special margin requirements of 100%, as can be identified here: https://www1.interactivebrokers.com...ag=United States&ib_entity=hk&ln=&b=FTP&e=GBO