Very unrealistic; they left out the part where you have to read a few dozen different specification sheets and reference manuals, only to discover that the parts aren't compatible.

In reality, circuits are built by making a schematic drawing, then laying out the circuit; many different decisions have to be made, and each of those steps takes days or weeks. In addition, you are probably prototyping important parts of the circuit while doing the schematic or layout; these early tests may be with physical hardware or in some simulation software. Spice simulators are more like an IDE than a video game, but they are very limited.