Technically this is about a mod, but is still Fortress-based, and I imagine like 90% of Dorfs use it at this point. Anyways, custom Roles is one of those things that you think about, but always get too caught up in playing to ever bother with, similar to creating Macros & Blueprints. I did briefly toy around with Optimization. However, I found the level of detail there to actually be too much, it was overwhelming. I finally set aside ~40 minutes to read and create. Wow, lol.
Using custom Professions is a little slower than Optimization/Roles, since you have to examine every Migrant. However, setting up the Professions is significantly faster and less mentally intensive, resulting in a net gain of time spent. Plus I tend to run large-ish Forts, so weighing a job against personality & population is less meaningful for me. The end result is a mass-production of Professions, very neat and orderly.
All of my Farmers have Brewing, Cheese Making, Herbalist, etc. I run enough of them to negate the few who detest being outdoors and subsequently barf on the food as they are making it. I merged Mason, Mechanic, and Stonecrafter. All Professions, even the non-haulers, have important 'hauling' activities such as Levers & tending patients/prisoners. The best part is I can still assign specialty labors after a Profession, if say for example one of my Farmers is also an experienced Bowyer.
So yeah, really pleased that I took the time to learn this, especially b/c I can now sort my Dwarves by Profession name and get a much more accurate picture of what my labor pool looks like.
Edit: Per request, this is my custom Professions file (not to be confused with Roles, which uses personality, weighted average, etc.);
Click Me!Few things to note:
1. Super-specialty labors like Pottery & Bee Keeping have no Profession. Should I want to start one such industry, I manually assign a Dwarf.
2. Medical skills have no Profession. If a migrant is skilled in one of the Medicine items, I just re-enable that labor after assigning a Profession. Also helps to ensure I only have my Chief Medical Dwarf with Diagnostician enabled.