I honestly barely recognise this 'monitoring and supporting dc's development' as a discrete task, never mind a massive one. I hung out with my kids, played with them, read to them, fed them, took them out with me etc. All just normal day-to-day family activities, largely the same as they did at the childminder's.
You would recognise it, if you had a DC with SEN! Then, you have it all explained to you for the next 20 years by say speech and language therapists, educational psychologists, occupational therapists, consultant development paediatricians, physiotherapists, CAMHS, specialist teachers.....They explain each aspect of child development, that they deal with to you, and give you programmes to do with DC to help them progress, where their difficulties mean they are not developing normally!
(I won't count SENCOs or ordinary teachers, as ime, they did not have a clue!)
Then there is all the research you have to do around the SEN, reading books, articles, the internet, attending support groups, lectures by academics in the field, etc; because nobody gives you a handbook on how to bring up a child with several SEN. There is a lot you have to find out for yourself! Then, you become much more aware of child development, and what are the normal milestones - and how to do things like teach language, improve attention, and behaviour management of a very scared child in a world, they don't understand and which does not understand them!
I am far more aware of how DGD's communication and motor skills are developing, and how to encourage language, etc, because I am aware of what the red flags are.