There is no "technically" about IACRA, it is an electronic 8710 form and it must be submitted and endorsed by the recommending instructor prior to starting the checkride. Or, you use a paper 8710 which must still be completed and signed by the RI prior to the start of the checkride.
Per 61.123, a commercial applicant must hold a private certificate prior to being eligible for taking a commercial checkride so how can an instructor endorse a person to take a checkride who really isn't qualified to do so? I'm sure some would look the other way and just do it but that's not a quality I'd really seek in a good instructor.
Technically yes but in the case of multiple checkrides in one day, where does one checkride end and another begin? If I take my PPL checkride in the morning, have the DPE sign off on the IACRA, take a break for lunch, during which time I am filling out and submitting my Commercial IACRA for validation by the instructor, and return 30 minutes later then you've done everything "by the book." There is no guidance I've seen regarding the specific length of the checkride, both oral and practical. The DPE in this case having already put you through the paces in the morning oral and flight session could in theory spend 10 minutes on the oral discussing what you're going to be doing on the practical before taking you out to do a lap around the pattern and call it a day and again it would all be above board/by the book. This is exactly what many do for the SEL/MEL Commercial applicant or SES add-on applicant... They go out and cover only those operations that weren't covered by the earlier checkride.
For that matter, when I did my own PPL checkride, I filled out the IACRA and submitted it for endorsement by my instructor and he assured me he endorsed the application the night before the checkride. I got the message from him just before bed and didn't think to check it in the morning with all the excitement and rush to get to the airport and do the checkride but it turns out he only digitally signed the form and didnt submit it. While I dont remember if it came up before or after the checkride, I know it wasn't signed until after the checkride began as it took a phone call to him to get him to hit submit. My log book however, carried all the necessary endorsements from the instructor and that's all the DPE cared about at the start. We flew the checkride, he went off to do his afternoon checkride and then I met back up with him in the evening to complete the paperwork after the instructor had corrected his error.
As to the quality of a good instructor; my position on that really depends on where the instructor is coming from. If the instructor doesn't know any better, well that's an education issue and perhaps they aren't an instructor you want to use but there are plenty of regs that even the best, most knowledgeable instructors dont fully understand and I dont know anyone who has all the regs (and their interpretations) memorized. I'd take the instructor who is clueless about regulations but really knows his s**t about flying over the instructor who doesn't know s**t about flying but can regurgitate regulations, any day of the week. If the instructor does it because he just doesn't care about the regs, then that's definitely an instructor you probably dont want to use. But if an instructor does it recognizing the spirit and intent of the law more so than the letter, I wouldn't quibble over that use of prerogative/discretion. Gaming/Working the system is not illegal and those who dont take advantage of it are either naive, stupid or both; their so-called moral superiority doesn't change that fact.
Regarding the endorsement required under 61.123; the FAR makes no reference I can find under this part or any other part to the IACRA being endorsed. Specifically, 61.123 calls for a log book endorsement from the instructor and there is nothing in the FAR's saying that the Commercial pilot applicant must hold a private pilot's license at the time of the checkride. In fact, an ordered reading of 61.123, places the requirement of a private pilot's license after passing the checkride. Additionally, the requirement merely says you must hold a private pilot's license under part 61 but it makes no mention of the category and class of aircraft of the PPL. 61.129 specifically refers to the application as a "commercial pilot certificate with an <insert> category and <insert> class rating" which is exactly how a SEL PPL can get their Commercial MEL or Commercial Glider or Commercial Helicopter or any other category and class rating in a single check ride and why if you want Commercial SEL/MEL, you must take up 1 of each type of plane during the checkride.
Regarding the qualification to take the checkride... Are you really trying to tell me that a student pilot without his private pilot license but who otherwise meets all knowledge, practical experience and flight proficiency requirements of a commercial pilot isn't qualified? The FAR's (and laws in general) are written by bureaucrats often in response to someone doing something stupid. They're there to keep the next person from doing something stupid but that also means that many of them lack a common sense outlook on things... This is exactly why they had to go and add so many exceptions into the FAR for military pilots trying to bring their military flight hours into the civilian world to the extent that most sections no longer even have specific exceptions and just blanket refer to an entire subpart (61.73) to explain all the ins and outs involved. But really lets look past those exceptions for a second and consider does a military pilot flying a 24+ hour sortie from Oklahoma all the way to Iraq/Afghanistan just to drop ordinance and return really not get to log that time as "cross-country" because they didn't land more than 50 mile from their point of origin? They just flew further on a single leg than most people will fly in any given week in their entire flight career and you're going to say they "arent qualified" because they didn't land there? Come'on man (yes I clearly know that military pilots do receive credit for this but it took writing in an exception to make that happen and by the letter of the non-exempt law, they would not)
