Summer programmes are marketed heavily to international families, and their value on an application is widely misunderstood.
Paid open enrolment programmes
Many programmes hosted on university campuses admit anyone who can pay. Admissions offices know exactly which ones these are.
Attending one is not evidence of selection. It is evidence that the family could afford it, and it is read that way.
Genuinely selective programmes
A small number of programmes admit a low percentage of applicants on academic merit, sometimes with no fee.
These do carry weight, precisely because the selection happened. They are also difficult to enter and usually require an application a year in advance.
What actually counts
What the student did with the subject afterwards. A programme that led to a project, a continued piece of work, or a sustained interest becomes part of a story.
A programme that appears once on a list and never again reads as a summer that was purchased.
The competing use of the summer
This is the practical question and it is rarely asked. A summer has one occupancy.
For a student whose test score is below the target, the return on spending that summer on preparation is usually higher than the return on a programme, because the score is a hard requirement and the programme is a soft signal.
That comparison should be made with the actual numbers in front of you rather than in the abstract.
The honest test
Would the student choose this programme if it could not be mentioned on an application. If yes, it is worth doing for its own sake. If no, the summer probably has a better use.