with this, are we recommended to put all open day type experiences in separately or can they be listed in one experience?That is far too much. Some experiences may only need a few sentences (eg open days, short placements, basic roles with limited responsibilities), while others may need longer descriptions if they have been significant period of times or varied responsibilities.
I’d aim for a work experience section to be not much more than 3,000 words in total and for many people even less than that will be required.