… is that you only need to administer one technical interview and one non-technical interview (each no more than an hour long).
In my opinion, any interview process longer than that is not only unnecessary but counterproductive.
Obviously, this streamlined interview process is easier and less time-consuming to administer, but there are other benefits that might not be obvious.
More effective interviews
"When everyone is responsible, no one is responsible."
Interviewers are much more careful to ask the right questions when they understand that nobody else will be administering a similar interview. They have to make their questions count because they can't fall back on someone else to fill the gap if they fail to gather enough information to make a decision on the candidate.
Adding more technical or non-technical interviews makes you less likely to gather the information you need because nobody bears ultimate responsibility for gathering decisive information.
Better senior applicants
When hiring for very senior roles the best applicants have a lower tolerance for long and drawn-out interview processes. A heavyweight interview process is a turnoff for the most sought-after candidates (that can be more selective about where they apply).
A lot of companies think that dragging out the interview process helps improve candidate quality, but what they're actually doing is inadvertently selecting for more desperate candidates that have a higher tolerance for bullshit and process. Is that the kind of engineer that you want to attract as you grow your organization?
Priors and bias
In my experience, people tend to make up their minds on candidates fairly early on in the interview process (or even before the interview process begins). The shorter interview process merely formalizes the existence of that informal phenomenon.
Especially at larger tech companies, the hiring manager already has a strong prior on a few applicants (either the applicant is someone they or a team member referred or has a strong portfolio) and they have a strong bias to hire those applicants they already knew about before the interviewing process began. Drawing out the interview process is a thinly veiled attempt to launder this bias with a "neutral" process that they will likely disregard/overrule if it contradicts their personal preference.
That doesn't mean that I think this sort of interviewing bias is good or acceptable, but I also don't think drawing out the interviewing process corrects for this bias either. If anything, extending the interview process makes it more biased because you are selecting for candidates that can take significant time off from their normal schedule to participate in an extended interview panel (which are not necessarily the best candidates).
Background
The inspiration for this take is my experience as a hiring manager at my former job. We started out with a longer interview process for full-time applicants and a much shorter interview process for interns (one technical interview and one non-technical interview). The original rationale behind this was that interns were considered lower stakes "hires" so the interview process for them didn't need to be as "rigorous".
However, we found that the interview process for interns was actually selecting for exceptional candidates despite what seemed to be "lower standards", so we thought: why not try this out for all hires and not just interns?
We didn't make the transition all at once. We gradually eased into it by slowly shaving off one interview from our interview panel with each new opening until we got it down to one technical and one non-technical interview (just like for interns). In the process of doing so we realized with each simplification that we didn't actually need these extra interviews after all.
