Wiring for concealed points need hacking means when the time we need to install additional lighting point and plug point?

You agak agak lah kitchen need direct DB points and make sure got at least six spread over, agak agak bedroom make sure enough for charger lamp vacuum, agak agak PC and TV rooms have plenty of sockets

Hack first beforehand. That will allow enough time for the patch cement to dry out (recommend 28 days) then only putty and paint last. Otherwise shrinkage cracks occur.

You have time, dont mind running around, then order your own material. get best value, at expense of time/energy. Not enough material, need to buy. Workers wont skimp on material for you, and likely end up wasting some, since not their cost. Many times i see if not their material , they dont bother, eg after paint halfway, just leave paintcan open, exposed overnight. Then later say paint bad quality, ask buy more. And any issues, you arrange warranty on own. Eg switch rosak, you get guy come check, they you take time buy/claim replacement, ask guy come to fix back. If got paint scratch at side when change, then arrange buy paint and either diy or get another guy come touchup.

You want easy no hassle, no need headache count material and keep track of usage/wastage, then get main con to paukaliau. Any issue, just call maincon kautim. Pay extra, but usually end up not that much.

Or pick and choose. Eg high area where susah to do yourself (eg need scaffolding), get maincon. Easier things, get own material.