More info on workbenches - without mods, vanilla workbenche = 200u sphere volume. Think of 1 u = 1 meter or whatever unit used for construction. e.g. a 2m wooden beam laid down 10x would equal ~20 meter = 20u.

But instead of radius, is a sphere shape - height up/down, and all directions as conical sphere. So if you don't overlap benches, you can have small spots around base where it is not covered. Even 1 tiny un-covered spot is fair game for spawn to occur. So what you want to do is either of 2 things:

a) easiest - get mod that increases workbench range. Personally use one and set to 800u. This is quite large volume of space, so 1 workbench more than enough to 100% guarantee zero spawns even with large base, plus provide safe cushion so that when raid does trigger, the raid mobs spawn far enough away it is not right outside my walls.

This is, however, because I don't like to build 100% immune bases, with moats, pits, and/or raised walls. Whenever raid happens, I go out to fight and kill them (it is after all free materials - 1 wolf raid and you are set on pelts for awhile).

b) non-mod option is do what mod does but manual way - instead of having 1 workbench with 800u spehere volume, put down like 5-17 workbenches. Draw a circle in your mind where center of base is center of that circle - that is your main center workbench.

Now put 4 workbenches down in a X pattern radiating out from that center - this covers you with ~380-400u volume (*mostly sideways as you aren't increasing your height but in practical terms unless building skybase, that's all horizontal volume is mostly what matters). Don't bother to exactly overlay it, just close enough - e.g. don't spread this X exactly 200u away from center bench, but ~180 so you are guaranteed complete overlap and no blind spots.

Now if you want even more 'owned' territory where zero spawns can occur, put down another workbench ~180-200u in every direction from the 4-X benches set down. This means total of 17 workbenches including very center one. This provides overlapping coverage with zero blind spots in approx ~800u which is so large unless you build mega-mega base, is plenty + safe spawn distance I talked about.

With 800u distance, any raid spawns take like 20-30sec just to walk/run towards your base so you have plenty of time to gear up, get outside base and fight them if that is your thing. If not, hide behind your moat/walls till timer is up.

Personally, I see zero functional difference in a mod setting workbench = 800 vs setting down a bunch manually. Just the tedium to do so manually. But up to everyone to decide what is fun vs tedium.