Here's my 2 cents on how I generally break it down:
"Break-in" is a physical process, mainly related to a woofer's suspension/compliance changing over time, but can depend on the driver in question.
Usually, the majority of permanent changes will occur within the first 48hrs. I usually get through this process by playing deep brown-noise to give the woofers' suspension a good workout. The X-Statik woofers really needs those 50 hours of break-in before they sound right, most other speakers likely wont need or change that much.
"Burn-in" is an electrical process involving changes between the conductor and the surrounding dielectrics. Cheap/budget components generally don't change much over time, and any small changes that do occur are done within the first 50hrs. Higher quality caps, like Sonicaps or Superior Z-caps, generally need about 200hrs of use before their sound settles.
Caps like many of the Miflex, Duelund, Jupiter or V-Cap ODAM caps, which are oil-impregnated require more time due to how the oil affects the burn-in process.
It's not uncommon for fresh oil-damped caps to sound good one day, then rough/edgy the next, then flat as cardboard the day after, that but how dramatic the caps change over time will depend on the cap and where/how it's used. Once they get to 400-500 hours they've mostly settled into their final sound.
For Burn-in, my process has been 22hrs on & 2hrs off, mainly to give the system time to "settle" and cool down between burn-in periods.
How much of a different it makes, I don't know, but that's how I've been doing it.
Burn-in and break-in won't fix issues if something is fundamentally wrong with a speaker, or component, but the changes that occur generally improve the sound over that course of time.
A cap or speaker that sounds "bright" or "cold" won't ~magically~ become "warm" or "smooth," but a component that is a touch hard/edgy at first, should soften up little by little over time.
