Autotrade trading limit confusion

How is Max lots for Options trades and Max minilots for Forex trades protective? By Max lots I assume you mean Max contracts? Obviously, the amount invested is a function of the underlying stock price. One contract of BRKA (current stock price is $164,990) is gonna cost a whole lot more than one contract of GERN (current stock price is $1.14). Shouldn’t you be using a max investment $ value instead?