Moving back. Del is correct in stating that it helps ATC when pilots adhere to the original descent restriction. Generally, it's easily achievable by retaining the previous rate of descent. Is it time to change the book rather than having people quote it, be "correct", and score points when there's no need?
The main reason that the descent restriction is not repeated ad-nauseum is because there isn't the transmission space on the R/T. If every pilot were to query the previous descent restriction and every ATCO were to re-qualify it with every subsequent descent clearance, we'd have to decrease the flow rate on the sector.
Are the descent restrictions generally due to standing agreements and not only do they allow silent handovers but also keep vertical sectors separated? Would a sudden change from a high rate of descent to a lower cause problems further up the chain?