I should also add that the type of school and children that attend your childs school does make a difference.
While I only have anecdotal evidence, the smaller, more affluent the school, the more resources they have and the calmer, more inclusive school you will find. These types of schools tend to have clientele that come from a stable home life, and so their stability is really of value to children who live with a brain of chaos.
For example, many public schools in the inner city are over full, and have more children coming from unstable homes. They are coming to school to learn to survive. They have no extra budget to help with the one on one. They may get the extra money for the extra hire, however this hire may be spread around, or they may use the money for something else. The bigger the school the more children that need the help, the higher the chances that your child could get overlooked. Be present in your childs school, work with the teacher and principal, come up with the ways that will work for your child to get them motivated, get an IPP, (individual plan) which has the goals of what to work on for the education side but also for the behaviours and such. It also has the diagnosis and what works and what doesnt work. When you have a meeting over the IPP you would want to have all the teachers present so everyone is on the same page. Communicate with the teacher by email daily to start, then work down to a couple times a week. Pick up your child atleast once a week just check in with the teacher about how the weeks going, and if there is anything that needs to be worked on.
I know teachers are busy, but a good teacher appreciates a parent who is willing to work with them to help their child succeed.