Footprint Creation Strategy for Common Packages

Hello everyone,

I'm new to PCB library creation and am currently facing some challenges in understanding the best practices for building footprints in Altium.

Specifically, I'm starting with a common package like SOT23 and am unsure about the criteria to use for creating a generic footprint that can be utilized for multiple part numbers.

From my research, it seems there isn't a universally recognized standard. JEDEC isn't universally adopted, and while IPC is often referenced, I haven't found a standard mechanical drawing for a typical SOT23 there. I could refer to a datasheet from a specific SOT23 chip manufacturer, but each manufacturer seems to have slightly different dimensions.

Furthermore, once I create this "standard/universal" SOT23 footprint, what criteria should I use to determine if it can be associated with a specific part number? Will the "standard/universal" SOT23 footprint always be suitable, or will I often need to create a new one? What tolerance values should I consider to decide if I can assign an existing footprint to a part number or if I must create a new one?

Following a discussion with an experienced PCB layout master, the focus of my concern is managing the slight dimensional differences found in datasheets for components with the same nominal package (e.g., SOT23-5) but from different manufacturers.

My specific questions, considering this discussion, are:

    Strategy for creating a "generic" footprint for a package like SOT23: Instead of relying on a single datasheet, what criteria should I follow to create a footprint that can accommodate most SOT23 components (e.g., by considering the maximum dimensions found across various manufacturers' datasheets)?
    Criteria for associating an existing footprint with a new part number: Once I have an SOT23 footprint in my library, how can I determine if it's appropriate to associate it with a new integrated circuit in an SOT23 package? What tolerance values should I consider when comparing the component dimensions in its datasheet to the dimensions of the existing footprint? Are there any guidelines (perhaps based on IPC or best practices) to establish if the differences are acceptable or if a new, specific footprint is necessary?
    Does it make sense to create manufacturer-specific footprints (e.g., SOT23-ST vs. SOT23-Texas Instruments)? What are your opinions on this approach, and what are the pros and cons?
    Library Guidelines: What general procedures or guidelines should I document for footprint management so that future library users know how to decide whether to use an existing footprint or create a new one, taking into account tolerances and dimensional variations?

I understand that experience plays a crucial role, but I'd like to define some objective procedures to ensure consistency in footprint creation and usage.

Thank you in advance for your help!