DS2 did year of Kip in English mid Y5 to mid Y6 and I wanted him to gain sufficient confidence to 'pass' his KS2 tests.
Briefly, he got a '2' at KS1, did Y3 in that school then transferred to another primary where he was routinely tested and got a '3' mid Y4!! The school gave him 10 one to one 1 hour sessions to help him catch up, then we sent him to Kip.
Personally, I think it was money well spent. He was in a group of 4 or 5 DC, all doing different levels of either Eng or Maths; the tutor sets a bit of work, either on their PC or on paper, leaves the DC to get on with it, moves to the next DC, sets or checks their last bit of work, sets another bit, moves on. In this way, you're not 'paying' the tutor for the time it takes for your DC to do the bit of work. There was always homework, either spellings or ordering sentences, or filling in appropriate words into blanks, or writing a short paragraph, all of which was marked and returned. I think it was about £27 for a 1 hour and 20 minute session.
The maths DC seemed to be working through structured worksheets; the tutor identified weaknesses, he seemed to break down the task then set a worksheet of easier examples of that 'weakness' til the DC had mastered it. It appeared to work, but I honestly don't know if that approach would help a DC who just didn't 'get it' at all, whether 1:1 tutoring might have been better.
I'd agree that it'd depend on how good the franchisee was but I was happy with ours.