In my early EE days, I worked in the transmitter development department at Hughes Aircraft. My job was to design and test different high voltage circuits used in airborne RADAR. Man we would blow up capacitors left and right. Always had a grounding rod nearby for safety but still got "bit" a few times.
We had access to the Electronics Store so we would get handfuls of the specified capacitors and hand tested them all till we found the right ones. Even then, temperature variations affected our circuits. We just basically used our scopes, spectrum analyzers, and other sophisticated test equipment to fine tune till we got it right.
Those were the fun days, late 1970s. I got to work with some of the pioneers in the industry. Many of them PhDs and others Navy trained. The Navy had the best electronic training of all the branches.