gets my stubble as short as a blade cut would be after 12 hours
This is a very pertinent point. I normally have my head shaved at the barbers each week but have a set of 0000 clippers for other times – very useful at the moment! After a day or two my barbered head is the same length as a full shave.
so bought a cheap Wahl (£12) to see if it cuts closer and it did but slightly
If you’re not bothered about trying to get it super short then a standard set of Wahls works great! Getting super tight usually needs something a bit more specialised that can fit a blade with lots of zeros.
0 = 1.2mm
0000 = 0.25mm
00000 = 0.20mm
Standard clippers with the plastic guards the pop on only go down to a 0. The ones with the metal clip on blades go down to the shorter lengths.
Hair grows at roughly 0.33mm (low end of range) per day so if you get a full tight shave it will typically go:
Day 0 = 0mm (bald!)
Day 1 = 0000 clipper
Day 4 = 0 clipper (1.2mm)
Day 8 = 1 clipper (2.4mm)
Having a shave buys you an extra day over a 0000/00000 and 4 days over a standard minimum 0 clipper.