I asked the same question, but you can keep taking cuttings of each generation and it will not affect the strain... I thought it was kind of like making a copy of a copy of a copy and so on, but this isn't the case.. I have been assured by a vet grower on this site...
So keep going, its just a lot more work and the timing has to be better, so you don't have clones sitting around waiting for your room... If you have mothers you can take them whenever you want, you don't have to time it with when you turn down your lights, and then you could have your clones sitting around for up to eight weeks...Unless you have another room they can go into...
I am aiming for four different strains in the one mother tent.... Just so I can pick and choose what I want to smoke....I have grown them from seeds so it's taking some time... Hope this helps... Just my two cents...
Also I didn't give my clones any fresh air, just 100% humidity, they root faster that way, they really don't mind the heat, think of a greenhouse....