When preparing for an initial issuance of a Commercial Pilot Airplane Single or MultiEngine Land please review 61.129(a)(4). The text of the regulation below. (b)(4) is written in a similar way and applies to multiengine. In any case, the regulation gives the applicant strict choice between either being SOLO (i.e. sole occupant of aircraft… no friends, no spouse) or meeting the requirement performing the Duties of Pilot In Command (DPIC) with a CFI onboard. To be clear the intent in the DPIC aspect is that if a CFI must accompany you (perhaps because you are not allowed to take the plane solo) then the role of the CFI is not to teach, they are supposed to sit on their hands and let you do the work. At the conclusion of the flight the flight should NOT be logged as DUAL. Instead they sign it, and notate it as DPIC time to meet requirements of 61.129 (a) or (b) (4).
If you’re questioning the validity of this position please checkout Grannis (2016). This is a legal interpretation from the FAA, they summarize that the pilot (Commercial Pilot trainee) must strictly choose between performing all 10 hours solo or performing all 10 hours with an authorized instructor on board. It is not allowed to do a few hours solo and the rest of the 10 hours with an authorized instructor on board, because there is no “or any combination thereof” language in the regulation.
(4) Ten hours of solo flight time in a single engine airplane or 10 hours of flight timeperforming the duties of pilot in command in a single engine airplane with an authorized instructor on board (either of which may be credited towards the flight timerequirement under paragraph (a)(2) of this section), on the areas of operation listed under § 61.127(b)(1) that include—
(i) One cross-country flight of not less than 300 nautical miles total distance, with landings at a minimum of three points, one of which is a straight-line distance of at least 250 nautical miles from the original departure point. However, if this requirement is being met in Hawaii, the longest segment need only have a straight-line distance of at least 150 nautical miles; and
(ii) 5 hours in night VFR conditions with 10 takeoffs and 10 landings (with each landing involving a flight in the traffic pattern) at an airport with an operating control tower.