In an article by Newsmax buyout firms are described to crave Warren Buffet returns, but in confounding consequence with cause, innate to the constructs these firms deploy today, fail to yield such returns. Courtesy not of money management voodoo, but of simple depravity of reason.
The debate for long or short depends (of course) on the causal connection with the risk deployed. Meaning the risk associated with the asset in question should dictate what asset-class or distribution bucket we put it in, and thus defines the holding period.
So, a debate about whether to have more long or short must be predicated on the understanding of the higher-normalization of value attached to the assets in question. Warren Buffet applies his own and unique assessment of the value of a company (based on a higher normalization of evolutionary risk than the pancake economics deployed by most money managers) and then decides how long or short to hold the equity. Not the other way around.
A holding period must be a consequence of the assessment of risk as its cause. Do not confound consequence and cause, or depravity of reason will murk your asset management waters.