Depends on your income streams in retirement.
I had less than 2 years in living expenses, but I had private pensions that covered 70% of living expenses so the chances of needing that cash was, I hoped, quite small.
In reality, one could have an extended timeframe to cover, yet still have little in cash.
For instance, in preperation for expected retirement in early 2007 for both DW/me, each had "sold off profits" from many prior years and had five years worth of cash (including taxes due on withdrawls).
However, since that time we have reduced the target by one year, becoming more comfortable in retirement without any income sources (such as pensions or SS) over the last five years. Of course, in our case we did convert part of our investments to an SPIA, which acts as a non-Cola life pension.
In reality, we are still living primarily on our investments, with two small DB pensions (DW) starting in June, and her FRA SS starting a year after that. In addition, I'll claim 50% of her SS as soon as she starts it, along with my SS at age 70.
Over the next five years, our cash accounts will be greatly reduced "in volume", but we still will maintain the current four year target in cash, regardless of other income sources...
I'll agree that it seems that most don't plan on keeping that many years in reserve, regardless of income sources. For me/DW, that's too little. But than again, we are getting more conserative as we age.