It's hard to speak for the average MP, not having been one myself. However, I recall that, back in 2015, there was a platform plank that the estimates were going to be presented simultaneously with the budget and reconciled with the budget. For a fiscal policy nerd, this was terrific news. Many provinces do it. I've never understood why the federal government does not. There are other countries with parliamentary systems similar to ours that do present their estimates at the same time as their budgets and consistently with them. I think that would be a great idea.
I think it is unnecessarily mentally taxing for people to see two sets of figures that are not on the same accounting basis and are not that well reconciled. It really shouldn't be necessary to reconcile them at all.
I would encourage parliamentarians to keep the heat on the federal government, because why not produce the estimates at the same time with the same accounting basis as the rest of the budget, which is consistent with the public accounts? There are many provinces that do it. They present them simultaneously, and they are reconciled. If they can do it, I don't see why the federal government cannot.