That workout from the other day wasn’t a good workout if you didn’t wake up the next day feeling like you were hit by an Acme truck.
Now, ain’t that right?!
Feeling like you were hit by an Acme truck, or delayed onset muscle soreness (DOMS), doesn’t mean you pushed your body hard.
DOMS is nothing more than the body adapting to stress to better deal with it in the future.
In other words, soreness is an adaptive response that dissipates with continued exposure.
So if you’re not new to weight training and find yourself still getting sore, that more than likely indicates that you’re working out infrequently, program hopping a bit too much, and/or your rest and recovery protocols are insufficient (e.g. not enough sleep, not enough calories, your macronutrient profile is inadequate).
The equating of soreness to workout effectiveness and muscle building is erroneous.
As the saying goes, correlation doesn’t imply causation.
I guess you ditched school the day that was covered!