BHD this is not true!
1mg is a compromise dose.
less than 1mg and it's efficacy becomes an issue in relation to hairloss
more than 1mg and it's side effects become the issue.
Finasteride is dose dependent.
The relationship between dose and DHT inhibition is not linear, that is 2mg will not inhibit twice the DHT that would be inhibited by 1mg, it tapers off in a non linear way so for example 2mg may only give you a 10% improvement over 1mg, with the associated increase in incidence of side effects.
I think, and this is a personal opinion, that if you are having no luck beating DHT at 1mg (and you need to give it a full year to establish this) and if you are not seeing problamatic side effects, it could be of some use to try a higher dose, say 1.5mg or even 2 mg.
There is a lot of biodiversity between people and some 6ft 5in american football player built like a tank may need a little more hormonal persuasion than a weedy 20 year old (no offense Chuj) with arms like pencils.
It is often quoted (by me occasionally) that 0.2mg of finasteride is almost as good as 1mg, but the operative word here is almost.
bottom line, in Mercks trials 5mg of finasteride grew more hair than 0.2mg.
but 1mg saw a good compromise between side effects and results.