The details are important. Calculations show the reality for comparison and accounting.
If you think of medicine career as a business you have to look at some metrics.
I notice the doctors here like to make things a bit vague for whatever reasons.

Whether or not the weekday and weekend hours are at different rates matters when you are considering taking on those slots. But on average that's what I got.

For that poster GP who has afternoons off his overall hourly rate is $107.93

Yes I left out CPF. And you conveniently did not elaborate on how much that is - giving vagary once more.

CPF contributions are calculated on a max of $6000 a month wages. 17% Employer contribution = $1020 a month. Employee contributes 20% of their wages (on max of $6000) =$1200 a month.

Hence the additional employer CPF contribution assuming the same poster GP is doing locum with the same clinic is an additional $1020 per month = $12,240 p.a

This would make his total annual income to be $236,740

His hourly rate for the 2080h worked is thus $113.82