Browning plaster is used as backing plaster to provide a layer to apply your final thin coat of skim plaster or multifinish plaster.
On areas which require a large amount of 'building up' it makes sense to apply some type of filler (for example expanding foam) so that you do not have to apply lots and lots of thin coats of bonding or browning plaster.
Bonding and browning plaster and backing plasters can usually only be applied in thin layers one at a time.
Wait for each layer to cure or 'go off' as plasterers say and then start your next layer.
Finish off your plastering by applying the 'top coat' which is referred to as 'skim' (because it is a thin 'skim' of plaster).
Applying the final coat of plaster is referred to as 'skimming' because plasterers use skimming plaster and apply a thin 'skim' of plaster to the walls or ceiling being worked on.