The GP is incorrect regarding how frequently TL dating is used. However, in general you have destructively test something in order to TL date it or work sampling into your excavation plan upfront. For obvious reasons, archeologists typically don't give 'cranks' access to archived materials to destroy, nor do they typically consult them when designing their excavation plans.

TL is very unevenly used, and mainly where nobody has already staked a claim as to how old the thing is. Proving senior investigators wrong is a good way to interfere with getting tenure. After they retire is considered a better time to find out if they were right.