Pennsylvania mechanics liens are filed with the county recorder in the county where the work was performed. So they are, in fact, filed. As for how long that filing process takes - a Pennsylvania mechanics lien can typically be filed in the public record quite quickly - even as short as the same day, if the lien claimant brings the lien in to be filed, themselves. Using a lien filing service (like Levelset) or filing a mechanics lien via an attorney may take additional time, but it should still be a very quick process, and either should be able to file a mechanics lien within a matter of days.
For more information about filing a Pennsylvania mechanics lien, the two resources below should be very helpful:
(1) How to File a Pennsylvania Mechanics Lien – Step by Step Guide (2) Pennsylvania Mechanics Lien Guide and FAQs
If you're interested in filing a lien using the Levelset platform, you can start that process here.