the capital allowance is equal to the net cost of the asset, i believe youre maximising capital allowances for that specific asset.
if the asset was in the main pool and i deduct its proceed from the main pool, and then apply 18% wdv to the balance. the capital allowance for that asset is not maximised, i.e the capital allowance will be lower than when i calculate its capital allowance separately.
i hope it make sense . study example 3 on the open tuition notes, it will make sense