No, it's not necessary.
But I follow www.ellopos.net/elpenor/lessons/pharr.asp">Pharr's recommendation on Lesson XVI -85 (pg30) which stated "5) Henceforth ... memorize not less than one verse per day till the first fifty-two are learned."
Normally I'll recite from the start (following the pronounciation scheme from one of the resource at textkit) and stuck at about verse 10. The best I've done is 20 verses.
I guess the first 52 verses are important to proceed further.

Don't let a pebble stop your pilgrimage.

I am still progressing, although very slowly. I've read the 1st 69 verses and turned back to the 1st 52.

I did visit the interlinear version, yes, is very useful for English structure reading, but I think the recital of a poem is of even more help.

Ha, revisiting this same post 1 year later and I am proud to say that I've overcome the 1st 52 verses. So, I moved from reading Pharr's alone and use various other resources to back me up. Anyway, I still keep Pharr in view.