How Biz Accounts flow to Personal Accounts without piercing LLCs?

[Ralph Chiaia]

I am a big fan of Profit First by Mike Michalowicz and have opened many accounts as he suggests to separate profit, tax, opex, own pay, etc. It's much faster and easier to open personal accounts than business accounts, so what I've done is opened biz accounts for my LLCs to collect rents and pay for things through Opex accounts which I'm calling "Maintency" (Vacancy + Maintenance), but then I pass profit, my own pay, and money I hold to pay taxes into my own personal accounts. Does that make sense or does that in any way weaken my LLCs' protection? I've heard that mishandling this can lead to piercing the shield of an LLC. I'd love to hear thoughts on this. Thanks!