I saw above a few replies back that old saw about increasing IAS to compensate for position errors when side-slipping ?
IMHO when side slipping (say to the left) the pitot sees the wind coming from the left at an angle, not straight ahead, so its forward component is less & it measures LOW. At the same time the air over the wing is coming at the same angle, so the chord it sees is increased, but it still functions as a wing.
[Depending where the static is it might not notice (balanced side to side types e.g. Jodel) or it could see a higher sideways component and thus read even lower compared with true airspeed - or the opposite.].
Consequently I always fly the same indicated speed on a side-slip as on normal 'finals'.
Increasing the speed even more seems to be at best arbitrary, is not in my pilot's notes and contrary to the aims steepening an approach to get in without gaining speed & thus excess energy.
mike