There are ways to do that, but there are a lot of complications.<p>First, most truly good workers, especially in the tech industry, aren't sitting idle for a long time, so they are often either being hired away from a job they already hold and possibly being asked to relocate.  A lot of those good people will not make a commitment like that to you and disrupt their lives if you aren't ready to make something of a commitment to them.  So, this might work well for entry level positions but probably less so for senior people.<p>Then there is the cost of dealing with them for three months or until you figure out if they are right.  While this is much less expensive than keeping the wrong person on for a long time, it is still very expensive.  Most managers want to try very hard to find the right person the first time not go through a whole series of short term hires looking for the right person.<p>In some situations this is a great idea (and what many companies actually do), but there are many occasions it is impractical.