Jameson has been building multisignature Bitcoin wallets for 4 years, first at BitGo in the enterprise setting and now at Casa for individuals. Throughout this time he has been writing and given presentations about what he has learned the hard way while trying to write robust software that can withstand both adversaries and unsophisticated end users. There is very little room for error in the crypto asset security space, thus it's important to learn from others' mistakes so as to not repeat them!