I have relaxed hair and it was doing fine as long as I was relaxing every 6 weeks or so. It was a lot thinner than my natural hair would have been but I was ok with how it looked. I have suffered misfortune for the past 3 year and was only able to relax every 3 months or so and may have gone longer than that a few times. Each time I relaxed, it was apparent to me that hair broke off because the two textures weren't compatible.
For my hair, if I get too much new growth, there will be breakage.
Hope this helps.