Singapore introduced changes to its assessment policy in 2019, lightening the load for school children. https://www.moe.gov.sg/news/press-releases/-learn-for-life—preparing-our-students-to-excel-beyond-exam-results; https://sg.theasianparent.com/singapore-education-system-changes
How are they doing? It is too early to tell but some teacher experiences to date are in the official magazine. https://www.moe.gov.sg/docs/default-source/document/teacher-digest/contact-jul19.pdf
Exams at the end of the primary stage of education are not uncommon. One difference between the situation in Sri Lanka and elsewhere is that the children are slightly older when they face such an exam. The Singapore Primary School Leaving Examination (PSLE) is a critical exam that is used to stream children into various academic paths, but it is offered to children in Year 8 of their schooling. If we take Age 5-6 as the norm for entry into school, the children in Singapore are 12-13 years old and in Year-8 of their schooling when they sit for the exam. In contrast in Sri Lanka, the children are 9-10 years old and in Year-5 when they face the exam popularly known as the Grade Five Scholarship Examination.
In recent years Singapore has been making further efforts to reduce the burden of exams on children. The latest reforms aim to drastically reduce the number midterms and end of term exam that students have to face.