exacting
ig-ZAK-tingadjMeaning demanding great effort, care or skill
Memory hook EXACT-ing: it must be EXACT. Chef Lin makes her new cook measure the sugar again and again until it is exact. A boss who demands that much care is exacting.
The exacting piano teacher made Rosa play the hard measure twenty times.
In context Repairing old clocks is exacting work: a single bent spring or a speck of dust can stop the whole movement.
Similar demanding, strict, painstaking, tough
Opposite easy, undemanding, lax
From the verb exact, “to demand,” from Latin exigere, “to drive out, demand”: ex (out) + agere (to drive).