MO 4 4post breaker in a home running both 110 and 220 off same breaker
It's called Grandfathered

If you build something, and it's up to code at the time, and they update Code, you usually don't need to tear out the work and retrofit.  

There are exceptions, e.g. for earthquake codes for high-value/traffic buildings, or ADA when you're doing a major renovation anyway.)  Wiring isn't one of them. 

It's really about quality of work

If the original system was properly wired, it is a great deal safer than newer work that is wired wrong.   

So you need to go through the system, with an eye for how it should have been built at the time.  This isn't far off of today, except for the addition of grounds.  

You can retrofit additional safety

In 2014 (really!) they amended Code to allow you to retrofit grounds at will. The ground path does not need to follow the other wires, it just needs to be large enough for the load.  

If you want to protect against failing electrical wires sparking and arcing and starting fires, you can fit arc-fault circuit interruptor (AFCI) circuit breakers. 

If you want to protect house users from electrocution (e.g. hair dryer dropped in bathtub), you can install ground-fault circuit interruptor (GFCI) devices.  These are commonly available as


a circuit breaker 
a "blank-face" device you put inline in the wiring
a "live-face" device, same as a blank-face except they give you a couple of convenience outlets 


They make dual-mode AFCI and GFCI breakers.  It's cheaper to use an AFCI breaker and a GFCI blank-face or live-face though. 

The four sub-panels are very good news.  That means if a subpanel is dangerous (FPE), obsolete (Pushmatic), cheap (Homeline), weird (Q-line), or just expensive to get GFCI/AFCI breakers for (QO/CH) -- you can swap the subpanel easily enough, without any serious danger.