In my opinion, no. Not that i've done one myself....but IMO the time between lessons is almost as important as the lessons themselves to let things sink in and think them over. Most have bad lessons/moments...I'd rather get that over with in one slot, then go away and calm down/get my confidence back, than know i was out for the whole day. Past a point in the week you'll likely stop effectively learning through fatigue or just getting annoyed and it'll still cost £25 odd an hour.
Taking normal lessons means you can determine and focus on particular areas of driving...lesson formats can be changed, you can take more/less or even change instructor if it's not working out, but taking a 5 day course you're committed to paying that full whack no matter what.
I did my theory before my lessons and that seemed fine, I'd rather use a free mock test than pay £25 an hour for some revision help from an instructor anyway. Remember it'll take weeks/months to get a test slot probably...is there any pressing reason you/yr mum wants it done in a week?