CQB - wtf?
FIBUA is proper term in SAF. Go through your BCTC, ICT, ARTC etc
then come back and talk. Those in 4SIR(?) who specalize in FIBUA
will have more to say.
The drill of entry is just that, a drill. Different situations,
changing circumstances n newer equipment will dictate new methods
of clearing a room. There are many virations and no one can say
which is better until you are on the ground.
Newer HDB flats with thinner precast walls - maybe standing up to
ignite gren may be dangerous (?). Entry through window, celing,
floor also possible to avoid being caught in predictable
patten.
Just a note - with steel grills over frount door/windows, maybe
breeching charge also may be too obvious calling card?