does it matter what t5 bulbs you use as far as how long they last.? Like will A 24inch bulb last the same as the 48inch or 60 inch bulb? I know if you over drive them that will shorten the life span but if you run them normally do they all last the same amount of time ? If so what is the normal time frame I hear 7 months and one year which is it? When do you change your bulbs out?