There are good & bad alcohols for hair.
The 'short-chain alcohols' like ethanol, SD alcohol, SD alcohol 40, Alcohol denat, Propanol, Propyl alcohol and Isopropyl alcohol can dry the hair.
But then there are 'fatty alcohols' that are good (or at the very least, not-bad) for the hair.
These include Lauryl alcohol, Cetyl alcohol, Myristyl alcohol, Stearyl alcohol, Cetearyl alcohol and Behenyl alcohol.

I remember I checked years ago and I'm pretty sure the alcohol in the NO MORE TANGLES is one of the fatty alcohols.
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AmericanJambo

To answer your original question, I know a couple of people that will swear using a scalp protector has really helped to increase their bond times and a couple of people (including me) that believe its decreased their bond time!
Its not that expensive and a bottle lasts ages, so its something you should try at some stage, especially if you do get an irritated scalp. Although I found using a medicated shampoo once a month worked just as well.
The one I've used is a whiteish bottle with red writing on it (can't remember the name) and Walkers have just brought out a heavy duty one.
You can also buy from any pharmacy 'liquid bandage' by Elastoplast which is a spray on liquid that coats & protects the skin, exactly like a scalp protector does.

As for knot sealer, again not a huge investment and it can prolong the life of a system by slowing down shedding.
As I think someone has already said, its a good idea to comb the hair in the direction you normally wear it before applying because its possible that excessive knot seal can fix the hair is a single direction, although I've never experienced that myself.