On a stock or relatively close to stock engine, that seems like significant overkill. Truthfully, a single wideband monitor on a stock engine doesn't make much sense other than Wow Factor.

Widebands are extremely useful for tuning modified engines. Even the experts at Pierce Manifolds who have been installing fancy race quality carbs on a broad variety of engines use them. Lots of racers use them along with other gauges that most of us will never have need for. Cylinder head temp gauges and exhaust gas temp gauges, for example(s).

Wideband tuning versus seat of the pants and plug reading saves an enormous amount of time. Typically, this is done on a dyno, so the operator doesn't have to worry about reading the gauge(s) while also navigating the road or track.

Cameron
Portland

I have one on the combined exhaust (I have the single outlet manifold). I use it to tune the twin SU carbs but to be honest, I get more out of the spark plug colors. When just lean enough to turn the spark plugs light tan, the AFR seems to run around 11 at idle and 13 at cruise. I have the digital read out plus LED's around the edge like Ron's article references.
dean

Tommy;

AFR Sensor sniffs exhaust and needs to be hot, so should be as close to the combustion chamber as installation constraints will allow...and that will mean one bung per cylinder only a few inches from the cyl head, and that you change sensor location during tuning (or fit 4 sensors and a switch if you're rich)...sensor located at the collector will obviously only see an average as the exh gasses mix, so is only marginally useful for tuning...

Sensor (or2) at the collector will also be sniffing cooler Exh stream so reading would be diff from just off cyl head. Characterization of the readings is necessary. With 4 bungs, after tuning operations, you can leave sensor in the location of your choice, and plug the unused bungs.

I advise edumacating yourself on AFR sensing and metering before haphazardly cutting metal...there's a lot to know, and more to get right and wrong...plus interpreting your AFR meter readings! I'll see if I can relocate a very good article published for the General Aviation / Homebuilt Aircraft constructors which had much good applicable info...

See also: https://www.sw-em.com/Carburetor_Additional.htm#Wideband_O2_Sensors ...not much detail yet, but I'm working on it...!

Cheers