Replacing bulbs??????

I have been growing since 2002.... i use 2, 1000w hps for bloom and a 600w mh for veg.... i was taught from my mentor to replace the bulbs every 6-12 months(the hps).. i know his reasoning, the belief that they loose their intenisty as they age.. i have seen many hps bulbs rated to last 24,000 hours.... if anyone has any facts on this subject i would be greatfull..... i have been shut down for the past 6 months and dont have the cash to waste on 2 new hps bulbs if its not necessary......

yah, every six to 12 months is pretty much what is recommended on all the sites and articles that i've found those far looking for the same info m8..

i'm sure you'd be ok to use the same bulbs, but just don't expect to get optimal output and growth rates is all..