track question

Hi all, Reading a lot about transitions curves and have a few questions. Are they prototypical? Are they necessary on model layouts. If so, why? Would they be recommended on all radius curves? I understand the concept and the how, but am fuzzy on the why. I'm guessing they might help reduce...

I'm a cabinet maker and know very little about trains. I have a client that wants me to build a suspended track for him. (LGB) The corners will be the #16000 track. R3-22.5 I have looked online for the dimensions and found that 16 pcs make a full circle (2486mm)97.9 inches round. My question...