If your business model requires proven profitability for a given hire, you may use some form of trial hire to make sure your new hire is profitable. Some 100% commission sales positions are a fit for this. Other roles typically involve a high percentage of hires that don’t stick for one reason or another. If the job is difficult and not very high paid, employees may have a tendency to give up or there might be a good number of unreliable candidates in that field. Other roles are technically specific and the ability to succeed is hard to define based on previous employment.
Trial hires can take a number of different forms. Temporary staffing is one solution. Low cost hires with a trial period can work as well. But there are drawbacks. Strong candidates in just about every field tend to be unwilling to accept a trial situation. Candidates willing to work through a temporary staffing firm are limited, so the talent pool that you get there is limited. Trying candidates out, hoping that they succeed, and moving on to the next candidate and the next candidate and the next candidate can be extremely frustrating, costly, and time consuming. Great teams that do great work are not built with trial hires.
The other strategy is to make good hires. Putting a process in place that greatly increased the likelihood that a hire will be good and profitable eliminates the frustration and cost of tryout after tryout. It takes a little work to create a hiring process that works, but once it is in place it will save a lot more work and frustration going forward and will allow you to build a really great team.