A Cascading Calculation, more often referred to as a nested calculation, is when a calculated value has one or more other calculations within it. This dependancy can be a factor when you change or delete a calculation and it is part of another calculations cascade. FileMaker doesn’t allow you to delete a calculation in this situation but it can be edited.
Creating a bunch of smaller calculations can be a bit redundant but it is more flexible (particularly in troubleshooting and copying/pasting code between tables). However, when taken to the extreme, having a large cascade of calculations that refer to other calculations ... that refer to other calculations ... (and so forth), can put a strain on your FileMaker databases performance.
Some developers are adopting the mindset of using startup variables instead of calculations in places such as this. So if they know that a calculated value is going to be used in many places, they use the variable method to toss calculated values up into memory instead of creating a separate calculation field.
There are advantages to this and there are disadvantages. Variables can be more flexible and don’t have the schema overhead of a calculation field. However, FileMaker will allow you to clear / delete a variable regardless of how you have decided to use it. So this can fall into the category of “with great power comes great responsibility”.