it aint a matter of what is the right size, the artist will look at the size of your wrist, the amount of letters for placement, your skin type etc…. if the writing is too small then it wont last the trials of time, and what you need to remember is that all tattoos spread with age…
if you see some people with very small lettering then have a look at them in a few years time, you will then understand why they didnt advise it.. the favourite is that the ones you have seen are either done by an unlicenced tattooist that doesnt know any better or its by an artist thats only in it for the money and dont give a rats arse what it looks like in time.
that should explain why most people have a phrase going down their arms or around the tops of them where there is more space to make it right first time 😉