The length of a spell or ritual is entirely up to you. Some like a lengthy spell utilizing multiple ingredients that are catered to the intent of the working. Some like more simple spells, with a few ingredients. Some people cast spells simply by harnessing and directing energy and often this done without tools.
As for chanting over and over and that's it. Yes it could work for some. It would work according to the energy and power behind the words used, not entirely the words on their own.