Not sure about point 1. Your PCBA can certainly handle design variants / conditional BOMs with SMDs, just the same as with TH. Or just place all three parts and add a jumper. The TH part seems more costly and labour intensive, and uses more board space.

Not worth it when your annual sales are in the mid hundreds.

I'd probably just go with a jumper in that case. Could even parallel several resistors of the same value for BOM reduction, too, if your different input voltages match up, which pushes you into lower price-per-unit brackets. The TH option is certainly valid, but I would question whether it's optimal or really justified.

"THT is faster and more reliable" ... For a single part on an already-populated board? Placement is always perfect and clumsy hands can hit a THT much easier than a pad. We also have space-constrained parts where the specific value is selected during testing, and even the 1206s I put down on that board with oversize pads are a struggle for our assembly team and a soldering iron. Better equipment would surely help, but again -- 100's of sales a year.

Fair. It's not a bad idea, per se, but I wouldn't consider it to be my first choice. Bit of a niche case.

@Polynomial -- why a jumper and not just a THT resistor? Multiple parallel SMDs would still need to be added or removed by assemblers. Removal is far worse than addition of course. I might see the value in a set of parallel resistors with scratch traces, but I think people fundamentally understand "add the right resistor" a lot more clearly than "cut this exact spot with a knife". But anything else still involves breaking out the soldering iron.

@MattS With the jumper you wouldn't remove the parts. The PCBA would fit all the resistors on every board, and you'd just short the necessary jumper pads with a solder blob to configure the specific value you need. No soldering components at all. And if your shunt resistances work out to be even multiples (e.g. 0.2/0.1/0.05Ω) you can fit the same maximum shunt resistance value (e.g. 0.2Ω) multiple times and bridge 1/2/4 jumpers to put them in parallel to get the final value required, which means instead of buying N of each value, you buy 2N or 4N of one value, which works out cheaper.

FWIW, I always spec THT parts if they're meant to be hand assembled, unless space constraints dictate otherwise. I agree with your comment but would counter that in 2023, all uses of THT resistors are "a bit of a niche case."

I understand now: solder blobs and not wire jumpers. In my own clumsy experience I find it hard to fix if you're clumsy with the iron. But definitely worth considering next time I come across this issue. Thanks!

:)

fwiw I do actually think your use-case is legit, and even combines with what I said in my answer regarding thermals, it's just probably the last option I'd pick.

and yeah, no, definitely not wire jumpers. I don't think I've used a wire jumper on a PCB in, like, 10 years haha

@MattS a good trick to use is to make a pair of pads that look like this: [> >]

if you use the same pad-to-pad clearance that your PCB manufacturer normally allows, but with the pointed shape, it makes it far easier to manually bridge with solder than if you just use two square pads.

also makes it more obvious which pads are intended to be bridged vs. which ones are just DNP'd.