A tape drive-implemented method, according to one embodiment, includes: using formatting information which corresponds to a magnetic tape loaded in the tape drive to identify wraps on the magnetic tape. Identifying wraps on the magnetic tape includes: identifying an outermost wrap on the magnetic tape on a first side of the magnetic tape, and identifying an outermost wrap on the magnetic tape on a second side of the magnetic tape. A procedure is also performed for each of the wraps identified using the formatting information. Performing the procedure for a given one of the wraps includes: sending one or more instructions to position a magnetic head of the tape drive over the given wrap, and collecting PES information which corresponds to the given wrap.