Whenever I learn a song, I am completely focused on recreating what was done on the recording. My main goal is to simulate the notes, rhythms, articulations, dynamics, etc. as closely as possible. However, there are certain times where the artist records a song with a free feel and most likely will not duplicate the song exactly as recorded each time they perform. Mostly, this occurs in strumming passages, certain solos, and other groove-oriented settings. Taking this into account can make learning a song easier because you have more clarity on what the artist was trying to achieve while recording.
For example, the song “Ten Years Gone” (and many other Led Zeppelin, as well as Jimi Hendrix songs as another example) opens with a very freely played intro using two chords. While you can recreate this with much time and work, I doubt that Jimmy Page ever intended to perform this passage note-for-note each time he performed the song. It is the feel, contour, and dynamic of the passage that he is striving to communicate. However, a song such as “Enter Sandman” by Metallica was refined and tweaked until just right, and they absolutely intend to perform the main riff the same way again and again. So, a student learning “Enter Sandman” should strive to simulate each note exactly as recorded.
Lastly, it helps to clean up tabs by locating any notes that may not have been intended, such as random open strings, muted strings, slides, unintended hammer-ons or pull-offs, etc. Again, this helps give you clarity as to what the important elements are in the passage for you to focus on. You may determine to keep these notes or eliminate them (depending on whether or not they contribute to the authenticity of the sound). For example, random open strings or mutes contribute to the authenticity of most Nirvana songs, so I definitely work them into my performance (such as the opening of “Smells Like Teen Spirit”). However, attempting to exactly duplicate the number of open strings, a random string mute, or an unintended slide of some sort sounded in an acoustic guitar strumming chord progression seems to be somewhat of a time-consumer and does not give me a good return on time-investment. One example would be the chord-strumming in “Wish You Were Here” after the main intro. If you take a broad view of the tabs, it is easier to play “in the manner” of the recording instead of exactly duplicating. So, sometimes you can interpret the tabs as “strum whole chord here, strum high notes there, and pick bass note(s) here” and get a very good simulation of the recording without getting too anal about strumming the exact number of strings written on the tabs.