It varies depending on the specific items. For example, there is significant money allocated to indigenous issues, notably claims settlements. On this one, it is much more difficult to predict the exact timing when funds will need to be disbursed, because it depends not only on the government's settling these claims but also on the aggrieved parties accepting the proposed settlement. It would probably have been very difficult for the government to anticipate that before.
The same probably goes for additional support for Ukraine. It is difficult to determine exactly when the funds will be necessary.
For other things such as the request by the Department of Finance for $2 billion to reduce backlogs of surgeries and procedures, this one could probably have been anticipated a bit sooner; but, again, others can debate that.
On leveraging transit funding by the Department of Finance to build more homes, this was a budget measure. It could probably have made its way into supplementary estimates (A), but officials will probably say that it would not have been possible.
We need to scrutinize each and every one of these big-ticket items to determine more precisely whether they would have been ready on time for main estimates or more likely supplementary estimates (A).