Slight drawback if we "just leave" we don't get the two years, do we?
And in "just leaving" there isn't an exit to negotiate.
May I suggest what you actually intended was to say negotiate a Trade deal?
And as an example The Canada-EU trade agreement has taken seven years so far
That is just the beginning of the problem.The EU has existing PTAs with 52 countries, and it is negotiating trade agreements with another 72 countries. In case of Brexit, the UK would therefore need to re-negotiate or start new bilateral negotiations on 124 trade agreements, plus one additional trade agreement re-defining its own trade status as a third country vis-à-vis the EU.
So to get back to where we are today we need 125 trade agreements as quickly as possible
You have to remember.
There is no framework for leaving. We are making this up as we go along.