In my humble opinion, Mock test do give u a decent idea of how the child will perform in the actual exam.
Mocks are pretty expensive thus given "mostly" by serious candidates or kids of parents with deep pockets

I would suggest sitting in Mocks not just by one provider but multiple different ones. Eg . Few from your coaching institute (if u have one) , but also from few others which are popular and known to have good cohort size Eg Suzan Daughtery or SuttonParent forum mocks.
If the child is performing consistently and remains in the top 1/3rd of the Cohort then keep doing what you are doing without creating additional stress in this last month of preparation

Cheers
P.S: 4 out of 100+ consistently is an amazing performance, so you're definitely on right track . If i would have been in your shoe, I will start exploring the bus routes to my desired school

. Good luck