Is it ok to use just one, regular shampoo for more than a month?

So what I want to know if you can use one shampoo bottle until it's over with out switching to a different one every week and then back to the old one. Is ok to just use one bottle? I mean I currently use Nexxus Therrappe Shampoo and it's pretty expensive. So do I need the second bottle of different shampoo? Thanks soooo much for answering!Is it ok to use just one, regular shampoo for more than a month?
if the shampoo makes your hair healthy and works for you, then yes you can stick to the same shampoo but other people prefer to try different ones when their bottle empties just to find the right one for them so if it is doing its job, stay with it and if it stops working as good for you, then that means that your hair is getting too used to the same shampoo and it is time to try a new one

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