In my first job in 1975 at Bristol Aerospace (now Magellan) we had a good aviation and NASA qualified draftsmen, but one kept making D and E size drawings so microfiche would not create false dots from optical blurring, so I had to convince him to use A, B, and C size maximum by condensing symbol gaps and reducing font size. Because I often had to work with 20 pages at a time.
In my next job, our draftsman was an illustrator who could convert any messy high-density drawing on a paper napkin into a beautiful readable work of art in hours, not days (like the block diagram of each chip on a motherboard). He ended up at my fourth job too and was the best draftsman we had, just like what one would see from Tektronix, HP and Hitachi.
Yes, they used symbol templates.
In the mid 1970s when we designed a system with about 40 PCAs we had no simulation tools and no quickturn PCB shops and no decent layout tools. So we drew it on a 4x scale grid Mylar with coloured pencils for G code track width and sent it to Toronto for optical digitizations. The checkplots were sent back in a week for approval and then boards in two weeks.
That was 1976. Fast-forward 15 years later; I made photo tools at a lithographic printshop from the design EEs the same day and two-sided boards ready the next day. For six-layer Getek and FPC boards, I got three quotes in one hour only using a table of numbers without Gerber files and had prototype boards (10) delivered in 48 hours to one week depending on urgency $xK.
I did the same thing for half-etched dotted-line tinned brass shields for 1 GHz radio shields for prototypes and had them made locally in two days using delivered two-sided phototools. Then the panel had breakaway tabs inside edge and could be assembled and soldered to board in minutes using high power soldering tools or micro-propane torch for walls with a removable folded lid (circa mid 1990s).
Here's a 4.5 GHz counter simplified schema & block diagram from the HP journal for an instrument we bought in 1976 with 1 Hz resolution:
When I ask OPs or users for specifications, I expect they will learn to have details like this and share the relevant ones. But often they are oblivious to the need for good specifications to make a good design.
Fast Forward to 1985 with this TEKTRONIX SA492 Spectrum Analyzer. This may only be 1% of the whole schematic and was done in an easy to understand and the manual was in a hierarchical manner like PADS dwg's were done.
This is one the best models for electronic schematics to follow and designers who choose REFDES for ease of locating from board to schematic. Earth ground symbol is important here because of the shielding design unlike triangle symbols which often ignore noise. Later I'll post the 32MB manual link from my dropbox. Experienced Current Mode Logic (ECL) designers will recognize the sub nano second latency and rise time logic here. LDO users should note the necessary RLC filters on the input for RF applications.