nanna. That is not practical because these parties do not employ prophets. They do not know what unforeseen event is going to affect the country.
Look back over the last 5 years, even a cursory glance brings up COVID, the war in Ukraine the currenet Arab/Jew conflict. Your country has had horrendous cataclysmic brush fires and floods.
With the best will in the world, catastrophic events like that can blow a governments manifesto promises right out of the water..
None of us know what world events, man made and natural are going to happen in the next 5 years. A super volcano explosion could give us several very cold years and mass crop failures. Global warming could acce;erate and coutries have to cut economic acrivity back to reduce emissions in a major emergency, Russia could fire a nuclear bumb.