I think MN is often polarised from real life, tbh.
I have rarely met a child for whom the diagnostic process is easy.
Taking DD1 as an example. Her pre-school came to me after 8 weeks. They observed her for the first 6 weeks, as she was so young (2.6). Then there was the Summer break, in which they hoped she would 'mature'.
After the summer break, they waited 2 weeks for 'settling' then came to me.
The person from the LA who observed her, deemed her 'immature', but given her 'behaviours' (she was frenetic, and wobbly, a bad combination), they put 1:1 in place.
We were one of the lucky ones, really, in that she started falling over for no reason 4 weeks later. She skipped the waiting lists, skipped the referrals procedure, and was admitted to hospital, when 3 consultants looked her over and decided which of them was most suited to look after her.
Now, to be honest, the likelihood is that they may still be wondering if she was 'odd' or 'naughty' if it wasn't for the fact that she started falling over. They did an EEG, and that showed epilepsy, and ALSO, crucially, said 'something fishy here, do a brain scan'.
She had an MRI, which showed that her brain isn't right. Various bits are all just a bit 'odd'. The lining generally is 'not quite right'.
It's almost exactly 3 years since I took her to the GP saying 'look, the LA woman says she needs 1:1, now she's falling over for no reason, there must be SOMETHING up'. (Incidently, I had taken her to the GPs twice before with falling over, and they put it down to viruses on both occasions.)
That 3 years has been taken up with EEGs, MRI scan, appointments, SALT, OT, Portage, and Statementing. She is starting her second year of Special School.
She STILL has no definitive diagnosis.
We are lucky, because they won't stop looking. There is enough 'hard' evidence (ie. MRI scan, motor skill issues, Speech and language, etc.) for them to keep searching.
DD1's just been entered into a brilliant study, Deciphering Developmental Delay. It will do genome mapping, hoping to find out why these children are developmentally atypical. There are 12, 000 children in the UK who will be recruited over the course of 3 years, and there will be thousands more who won't even hear about the study, let alone be able to get their child into it.
It is unusual for children to get an easy diagnosis. Truly. I think one of the easier ones is ASD, because the criteria is so rigid, and is so 'external', ie. it is the 'behaviours' of the child that leads to the criteria being met. Even then, there are so many children with ASD who are known to the system and trawl through it for years, not getting a diagnosis until they are 7, 10, 13.