Professionals need to take their “beta” (that is, the correlation of their career to the stock market) into account before investing.
Some professionals, like academics, are inherently low beta, which means they can invest more aggressively. Others, like architects, may find their work flow highly dependent on the state of the economy, and so require a more conservative approach.
For attorneys, it depends on their specialty. A bankruptcy attorney can invest quite freely, since his labor income and the stock market are up at diametrically opposite times. A corporation lawyer might find his fortunes rising and falling with that of the industry he works in. Still others will find their incomes unrelated to the stock market.
As a rule of thumb, you should have to consider how your income held up through the downturns in 2000-2003 and 2007-2009. Then, on the flip side, look at how you fared over the boom from 2004-2007 and 2009-2013. To the extent that your income moved in lock step with to the larger economy, you should have less exposure to stocks, because your career itself is like a stock.
You also need to weigh how many years of earning you have left in your career, the possibility of your being let go at some point, and how much difficulty you would have ramping up again. All these factors impinge on your portfolio design.