For me, the choice between whether to use Single Select or Linked Records (in another table) is largely pre-determined by whether the information in the field has related information that belongs in its own table (whether you bring that data in as Lookup fields or leave them in the linked table).
Examples of data I would change to a single select field (if you had been setting these up in their own tables for some reason)
- progress status (Ready, Pending, Done, etc)
- category groups (Tool Purchases, Rentals, Personnel)
- options that trigger various automations
Examples of data I would keep in a linked table:
- Clients, since each client has related information (phone #, address, etc.)
- Projects, same logic (project start/end date, budget, project lead, budget, etc.)
If you try to convert the second type of information to a Select field, you run the risk of having to, for example, re-enter the same email address each time you choose a particular Client from a Select field... this leads to loss of data integrity pretty quickly when you have many instances of that Client in your base.
