Just throwing this out there.....
As a guy who does weddings and corporates, and has limited time, I wouldn't spend over 5 hours on a simple tune like BEG. It's just not an effective use of my time. IMO, that amount of time should be spent on learning songs with more complex arrangements like 'Last Dance' by Donna Summer which is a staple for weddings and corporates. My band has a songlist of over 250 tunes, and although I don't expect everyone to pull each and every song off the top of their head, I do expect them to have it prepared for the gig. In a one month span, it's not uncommon for us to play 80-100 different songs, including a bunch not on our list. Quite a few of them will be played for that event only. If I spent 5 hours on each tune, I'd be spending over 500 hours (3 months of a full time job) to get a few gigs worth of songs down. Because we just don't have that kind of time, we use charts to help us learn and retain.
As a band leader I would be impressed if someone learned a tune note for note, as long as it's not sacrificing learning the arrangements to other songs. For me, I'd rather have someone play the arrangement well for all our songs than a portion that they nail note for note. The song that you nail note for note may not be noticed or appreciated, but the arrangement that you execute or flub will be.
Take a look at bar band song lists vs wedding band song lists. Sure, there's lots of crossover, but take a look at the songs that don't cross-over. Not only are the song lists larger for the wedding band, but they tend to be more complex arrangements. Any competent bar band can play BEG and have people sing 'Sha la la la', but they all can't nail the many changes in 'Last Dance', the harmonies in 'ABC' or have the stylistic diversity to play a Bossa Nova. Nothing against bar bands, as I play in them and they have their own set of strengths and challenges.