With regards to calls of 'maintaining FLxxx', or 'reaching FLxxx' I think you may find that these calls are an SOP at the particular airline(s) and are therefore a required call from the crew whether ATC expect or require them or not.
To not give the call would leave a crew open to accusations of operating outside their SOPs ( Yes some companies are THAT pedantic), regardless of what the crew may individually think.
Now I can fully understand how this may drive an ATCO insane after a while - but the answer is to put it in writing to the CAA who should request the particular company(s) to review their SOP in compliance with the CAP 413, or if the operator is registered outside the UK will write to the national authority of registration of that carrier.
Getting short with the crew over the RT helps no-one
