Either is ok.

Agitation should be done according to the instructions for the developer (and other chemicals) because different developers vary in chemical process and so do films and the photographer’s intent.

The Paterson instructions are a place to start. When the lid is on properly, the tank won’t leak when inverted and inversion is usually an acceptable method of agitation irrespective of developer used, the film stock, and photographer’s intent.

But because developing film is often an art, a good analogy for a Paterson tank is a kitchen appliance: the instructions for a slow cooker describe how to plug it in, turn it on, and the importance of using the lid, but a recipe will have more detail and might include additional steps such as overnight marinading in the crock prior to cooking, occasional stirring, or even cooking without the lid.

Learning to develop your own film means you will make mistakes and learn from them. Some of the mistakes will be big and the roll will be lost. Some will be small and you will try to do it better next time. The only way to learn is to do it and mess up sometimes.