I'll try to keep this one short and sweet.

Between mid-October and early December, I'd accumulated a very tasty 30%. In the space of a week I'd given half of that back - God Bless Christmas coming when it did to take me out of the market and allow me to reset.

What frustrates me the most is that I knew I was being a fool while I was doing it, but I kept doing it!!

Although I have Daily Loss Limits (3%) which I adhered to, I kept going back day after day despite knowing I was in a foul mood and throwing money away. It sounds incredibly silly and utterly ridiculous, but I did it. And can't imagine I'm the only one to have ever done it and won't be the last :P

Does anyone have any metrics, criteria etc. that they use to tell themselves "Bro, just walk away for a month"?

I trade intermediate and longer-term time horizons.
I have the luxury of not having to trade to pay the bills (dividends from our market index funds cover out living costs), so I can pick and choose the market periods when I trade.
I use a sequence of outcomes rule.
When I had much less capital to trade, I would risk 1.5% of my trading capital for each position.  If I had 3 consecutive losing trades (hence, drawdown -4.5%), then I'd stop trading for 2 months because it was clear that my trading system was out of synch or not suitable for current market conditions.  2 months was the minimum I believed it would take for market conditions to move on, provided we were in a bull market.  Obviously if we were in a bear market, I'd have to wait until the trend turned because I'm a long-only, trend trader.
Now that my trading capital is much larger, I only have to risk less than  0.5% of my trading capital, my sequence of outcomes rule has been extended to 5.
At any rate, if you find you have consecutive losses, then it's likely your trading system or even you personally (if you're more of a discretionary trader) might out of synch with current market conditions.  You may need an explicit quantitative rule to stop you from trading.  It can be based on number of consecutive losses or a % drawdown.
This is only my 2 cents, but a "stop trading" rule seems to work for me.  Sometimes the best thing to do is have an objective, quantitative rule that gets you to walk away so you don't revenge trade.