I would have to agree, you have been very lucky. Yours is definitely the exception, not the rule.
According to FAR 61.55..
Sec. 61.55 - Second-in-command qualifications.
(a) Except as provided in paragraph (d) of this section, no person may serve as a second in command of an aircraft type certificated for more than one required pilot flight crewmember or in operations requiring a second in command unless that person holds:
(1) At least a current private pilot certificate with the appropriate category and class rating; and
(2) An instrument rating that applies to the aircraft being flown if the flight is under IFR.
(b) Except as provided in paragraph (d) of this section, no person may serve as a second in command of an aircraft type certificated for more than one required pilot flight crewmember or in operations requiring a second in command unless that person has within the previous 12 calendar months:
(1) Become familiar with the following information for the specific type aircraft for which second-in-command privileges are requested --
(i) Operational procedures applicable to the powerplant, equipment, and systems.
(ii) Performance specifications and limitations.
(iii) Normal, abnormal, and emergency operating procedures.
(iv) Flight manual.
(v) Placards and markings.
(2) Except as provided in paragraph (e) of this section, performed and logged pilot time in the type of aircraft or in a flight simulator that represents the type of aircraft for which second-in-command privileges are requested, which includes --
(i) Three takeoffs and three landings to a full stop as the sole manipulator of the flight controls;
(ii) Engine-out procedures and maneuvering with an engine out while executing the duties of pilot in command; and
Note: this is not being PIC, but executing duties OF PIC
(iii) Crew resource management training.
My questions to you are: were your 3 TO/LDG done on the first flight? Have you complied with the above criteria (OEI, CRM, etc.)?
If you flew a leg and landed, the next day flew a leg and landed, and the same on day 3, you were in no way compliant with 61.55 and therefore in violation as was the PIC/company with whom you were flying.
An aircraft that requires two pilot's, both MUST be qualified and current in order for that aircraft to fly. There are a few exceptions but in a very gray area of the FARs. I highly doubt the FAA would "sign off" on the dual given argument if it's done during a normal company flight with passengers on board!
I'm not questioning your training but I am trying to point out the slippery slope you're on.
2000Flyer