Models which are functional, or part of an assembly, must be tuned and calibrated
After Model Source Design Categories, then Hybrid Models, the next discussion topic is Special Design Techniques. Some part should be designed with more-less chamfering on the bottom, or put on a raft. The slicer maybe adjusted to decrease the temperature on the first layer, the gap of the nozzle could be increased. Some parts, however, need far more than that.
When sealing the end of a steel pipe, for example, the model going to be scaled to the purpose (how long of a segment, how tight of a fit, how strong wall). A round profile might not be the best choice, a square or a hex profile with less contact surface could be better. The pipe could be heated to have a tight fitting plug take up the form of the pipe and result in a better, longer lasting seal. The plug could wrap only on the outside, could plug in the inside, or both...
Some design choices are simple, some require more. Some are golden rules, others offer best results, and some are mistakes. This is the forum to discuss how to best fit the pieces together.