Complex sentence: For ICs, unlike PCBs, physical measurement of the parasitics is almost never done, since in-situ measurements with external equipment are extremely difficult, and any measurement would occur after the chip has been created, which is too late to fix any problems observed.
Split into simpler sentences: For ICs, unlike PCBs, physical measurement of the parasitics is almost never done, since in-situ measurements with external equipment are extremely difficult. Furthermore, any measurement would occur after the chip has been created, which is too late to fix any problems observed.