Depending on the way you want to use your Table Lookups, you may design your business rules in a few ways.
Scenario 1 - Table Lookup outcome compared against different values
Creating a Table Lookup and comparing it against different values (like Table Lookup > 500; or Table Lookup >= 1500, or Table Lookup < 50 USD, etc) in the Conditions part of the Business Rule.
In this scenario, it is recommended to "refer" to the Table Lookup name as shown in the screenshot when comparing the outcome of the Table Lookup with different values.
Scenario 2 - Table Lookup outcome compared against the same value
Creating a Table Lookup to determine if the result is equal to a certain value e.g. Business Class; if it is True it returns a value of "Yes" or "No" if it is False as shown in the screenshot.
If you want to always get an answer within the Table Lookup usage and the same logical condition is used in multiple business rules, it is recommended that the logic is defined as its own business rule.
Once a business rule is saved, it can be referenced or cascaded into other business rules by selecting the "Other Business Rule" feature.
Things to Note
If the Table Lookup is used multiple times in a calculation there should be no performance strain placed on the system as the table lookup would be run once (results would cache from the first run and be used in subsequent runs).