And yes, we always tried to take the carts full of SD cards and memory sticks, rather than cauldrons and sinks!
I work in logistics consulting (including WMS config) and used to work in a company that had very in depth performance management calculations - and it did account for things like the size of items to be stowed. This is standard functionality now in tier-1 warehouse management systems.
Basically there are two parts - goal setting where the system works out how long a task should take (based on distance, acceleration for the equipment type being used, product characteristics, level of picker experience, fatigue etc) and then there is a performance calculation based on a re-calculated target time based on what actually happened and how long it actually took (usually a %). You have to recalculate the target to account for the fact that, for instance, the object could have been stowed at a different location than the system estimated if put away is system directed.
While an individual worker might get a %, a more typical department kpi will be items stowed per hour for instance. This is because these calculated KPIs are terrible for management of overall site performance because they only measure how ‘hard’ you are working, not how smart you are working (eg you might be generating lots of unnecessary travel but still scoring high in the %).
And some sort of half-version of this has been going for decades. In my first warehouse job we used to have a legacy warehouse system but had worked out performance targets which varied by the make-up of work you got (e.g. a combination of total weight picked, types of order you had picked, orderlines picked and units picked).
IMO the only difference is that these new algorithms are generally 'fairer' (the old issue was that rogue department managers could to give preferential treatment to some employees, or put them on the 'best' jobs) but they are also more complex and opaque, which leads to employee mistrust.
Where I worked a union actually audited the calculation so it is possible to do this in a somewhat 'open' way, although the problem with opening the algorithm up to everyone is that it is complex and can be easily misunderstood/misinterpreted, particularly if you do not have training in how it all works (which then also requires WMS training!). There were always misconceptions with how the calculation works, because all users saw was a rolled-up number and it's quite a complex thing to understand (even department managers would describe how it works wrongly, and the union would also describe it wrongly, which would confuse people further which obviously isn't a good place to be).
Sure, there could be a case where the chemistry between line worker and manager doesn't work out. I think these cases are rare and people must find alternative arrangements. We must be productive since we produce in a first world nation on an international market and line workers are low wage workers, no illusions about that.
We can calculate needed material and expected output. We plan with that. If that is reached, we have succeeded. People help each other when things go wrong. Far better than a mediocre developer fantasizing about KPI and making stop watches for people taking a shit.
Obviously creating a condition where workers are competitors might be a hindrance here. No wonder your factory sucks on productivity, everyone is a adversary and if others are slower I will look better on performance sheets. Genius management approach.
I'm not going to debate if it is / isn't a good thing, because that's individual opinion, but in a distribution setting these systems absolutely help improve performance/output when put into a DC operating at Amazon-scale (at smaller warehouses it's pointless).
> We have that too in our production, although it isn't down to the individual
Fair, I mean specifically individual user performance tracking has been happening for at least 30 years - because it used to be in a legacy system I used to use. And the time & motion based performance management a-la-Amazon has been around at least 15.