I am taking o levels this year and hope to get A1 for Emath and Amath. Is it better for me to continue wworkig on tys repeatedly or should I work on prelim papers
both
You can try redoing tys 2012-2014 and doing some good schools' prelim papers.
If you got no time already ,then doing tys is more practical
definitely TYS. Do not waste time on prelims as the questions depend heavily on which teachers set the papers. You want to get used to the GCE O level exam style and the way they ask questions.
i think some prelim papers are more helpful? cos prelims are harder than O levels so maybe if you do well in past prelim papers O levels wont be as difficult