No.
killing power to the writer is daft, unless its external then ok i guess you might as well, tho it wont make much difference. only way to prolong life is to use a normal cd drive for general (i.e. disk reading) use, but hey if you dont already have a normal cd drive, then dont bother buying a CD drive just to prolong the cdr drive life, thats daft. only reason to have two cd drives is for burning on the fly (direct cd-cd copy, without going thru HDD first) or because you already had a cdrom drive and its sensible to keep it.