A clearance search tells you whether somebody is already using the name you have chosen, in the class of goods or services you intend to sell under it. It happens before you print anything.
The alternative is finding out afterwards. By then the name is on the packaging, the domain, the app store listing and every invoice you have issued. A cease and desist at that point is not a legal problem so much as an operations problem, and the cost lands across the whole business.
Registration on the federal register also gives you something a common law right does not: a presumption of ownership nationwide, rather than only in the geography where you can prove you traded.