I'm often told by friends that cutting hair will trigger it to grow faster. But how do the roots know when the ends are cut? It does'nt. Hair is dead, like fingernails. We all trim our nails but no matter how often we do it, they still grow at the same rate.
My firm belief is that hair growth and thickness is built into your genes and can only be influenced by hormones/drugs. Nutrition is also a factor. The only things you can do is avoid hair damage and have a healthy diet.
What's probably kept the myth alive is that as a consequence of trimmed hair, there's less chance of breakage when brushing/combing because damaged hair tangles easily. Fresh cut ends also gives the impression of fuller hair.
My ends were so ratty that not even detangling spray helped pass a comb through my hair. It was silly of me for not trimming properly. My hair snagged and shed with my daily brushing. The ends felt like straw. Not even the "search and destroy" method of cutting split ends helped. Getting rid of forked splits still left behind the majority of damaged hair. Once damaged, it will not be healthy again.
Keeping strangly old ends is not worth it. I'd rather just maintain healthy hair so I had proper trim today. I only had a cut about three weeks ago but asked for 1 cm off (the previous was three months ago.) The hairdresser said I needed an inch off so happy to agree.
My hair feels smoother and I no longer have crunchy thin ends. It looks and feels healthier and I don't lose so much hair when brushing. I will keep up with the trims from now on!