I heard from a senior that...
When a certain bus gets new WAB
buses, they have to dump the old non-WABs somewhere else, like how
they dumped the VOs on 23, 65, 74, 132, 153, all JIS services etc.
instead of making them SP buses.
965's case is because SMRT chooses to dump the O4s on 965.
163's downgrade earlier on was due to HGDEP still having lots of
MK3s at that time, and had to deploy them on certain services.
70's case is due to not enough SP WDDs at AMDEP, as mentioned by
SBS 9631X. Don't think ADD to WSD replacement is good, as it is a
high demand CBD service.
That senior sounded bright......not.
To put simply if you put the older buses into SP, then what's
"deployment of assets" for?
Might as well Russian Roulette every morning?

I won't even call it "dump". It's called "re-shuffle".
Please get your mannerisms right.