There are a number of reasons you will often find advice for specially orientating your models for printing with resin. One of the first reasons is to reduce the amount of supports required.
Angling your model 30 to 45 degrees instead of upright at 90 degrees from the build platform, can reduce the number of overhangs. When angled, these areas are able to build off themselves, without the aid of a support.
Another significant reason, specific to DLP and LCD SLA printing, is by angling a model that is tall, you are reducing the overall height of the model. In resin printing that cures a whole layer at a time, height equals time. This is a simple way to reduce the time, but reducing the number of layers required to complete a model.
Another very important reason to angle your model, is to avoid large surface areas. By strategically tilting the model on the X, Y or Z axis (or in combination) you can reduce surface area for each layer, depending on your model. Reducing surface area helps reduce the force required to pull each cured layer from the FEP film, thereby reducing the risk of layer lines.
There is no one-size-fits all approach to model orientation however, as all models are different and will require slightly different approaches to orientation and supports.
However, if your model has a large solid base, and generally builds upwards from itself without significantly large surface areas (such as figurines and sculptures), orientating your model may not even be necessary and you may achieve greater quality printing the model’s base flat on the build platform.