Yep, just like learning anything the intro level summaries don't reflect reality they just help you get your head around new things.

In the real work experience every project, team, and company are a little bit unique in how they respond to the requirements and politics of the moment. Everyone is trying to get something done and how purely it follows some pattern or rule is only relevant as far as it helps get the work done.

What you learned wasnt useless - it was probably very helpful for understanding or at least getting exposed to lots of concepts that you'll need. However, just like the joke about physicists and their spherical cows, the perfect algorithms and architecture rules from school aren't even close to the whole story in the trenches.

A non-engineering anecdote - had a math professor tasked with determining a fit line for and integration of a bunch of sensor data (needed the total area under the curve, classic math test problem). College me imagined trying to craft bespoke integratable functions and maybe some multi part fitting optimization but I knew my little list of memorized formulas couldn't touch this real life data so I was looking forward to the veteran approach. Math guy printed it, eyeballed to fill in the gaps with a pen, cut it out, and weighed it against a sample of "1x1" unit squares of the paper.

I was flabbergasted but the dude was so obviously right -- one off task, collected data with no clear pattern, didn't need crazy precision. The "obvious" answer took far less time than anything I had in mind and was plenty good enough for the problem at hand.

tl;dr - what you learned so far wasn't wasted it was simply the very beginning of filling up your mental toolbox