Also try to see how "easy" the process is in your own country

Yes unfortunatly many rules applies due to the few that try to break the rules !

I am doing the same - likely stupid - also do not like to wait - guess something engrained about moving forward - then comes possibly customers, the luggage, the paying for parking and on it goes

Likely different from office to office in Srischa they require same day in the morning - which we have done for 7 years - no issue as we can pick it up from a lokal Bangkok Bank in Srischa at 08.00 and immigration opens at 8.30 plus over the years the number of visitors to immigration has gone down and the number of people at immigration has been the same.