Just seen Sam Gyimah, the most recently resigned minister make one of the best contributions I've seen in the Commons.
I do disagree with his conclusion, but he does raise points seldom heard.
If you can get it online, it's worth watching, or reading later on Hansard.

The main one that struck with me was that we have a non-binding declaration on the future relationship.

But the EU has elections next year, will be focussed on that and we will lose a year of the transition due to this.

Then we will have a limited period to conclude, working with a new Commission, on the basis of a non-binding agreement with a previous Commission.

He feels we could be forced in to the transition extension having made little progress (extra costs) and more or less held there until we agree to something that favours the EU as we have a clock ticking on Northern Ireland (to avoid a customs border down the Irish Sea) but the EU has all the time in the world as they have an annual fee as long as we stay in the transition extension.