@mino I’ve managed to maintain my ignorance about concrete/cement for many years but if you’d like to explain the difference I’ll pay attention.
You said a cordless drill is good enough to mix a “nag or two” of prepared concrete.
Then at the end of you post you said “Concrete from one or two bags of cement is a different matter”
Would you elaborate please?
"Bag of cement" as a measure of concrete quantity => over here we make LOTS of stuff from concrete, way more so than from wood. So purchasing "concrete" bags is seen as cost-prohibitive and done only for very small jobs, mostly inside buildings and such. There a good cordless drill is all that is needed.
For anything bigger, the concrete is made from ingredients with only cement being in bags. The way to quantify the amount of concrete is thus often done in "of bags (of cement)".
As you know, when making concrete you need water + cement + sand/gravel/stones in a correct ratio where the water-cement ratio is the most important while one can tune the gravel/stone ratio a bit. ref:
https://en.wikipedia.org/wiki/Types_of_concrete#Modern_concreteSo concrete (quantity) "of one bag (of cement)" is equivalent to 5-10 bags of pre-mixed concrete. Or 50-100 cubic liters.
Folks would usually have some gravel/sand pile ready at their property - bought in bulk - and only purchase cement bags as need since those are tricky to store long term. This is also common on (small) building sites that do not have reliable dry-storage for cement.
ADD:
Reading again the OP post, I think I unconsciously mind-translated "yard or two of concrete" into "meter or two of concrete" and then applied the non-length meaning of "meter"*) to it, ending up with concrete quantity of 1-2 bags (of cement). Woohaa!
Sorry for the confusion. Just now noticed the "yard" in there ... which is certainly not a measure of volume or weight ...
*) A "meter/metre" of something is here a common saying for "100kg" of something and in some cases also "100 litres" of something. Depends. Hence concrete of one bag (of cement) can also be (about) 1 "meter" of concrete. This stuff with coloquial units can get messy.