IMO as someone who has done hiring at a FAANG and many other companies, short answer is no, if anything it's the opposite. As long as you hit a sweet spot of staying at each place for at least 9-12 months with no gaps in between jobs--in reality, this means "it doesn't look like you were fired"--switching jobs not only makes you look more motivated, it also gives you a wider breadth of experience to draw from. A senior engineer at Amazon for 8 years knows how to do things the Amazon Way. A senior engineer who was at Google, Meta, Netflix and Amazon for 2 years each knows how to do things four ways, and as long as they can intelligently compare and contrast the way those four companies operate and the pros and cons of each, would be an extremely valuable asset.

The only time this would maybe not apply is director/VP level roles, though if you're switching at that level you presumably have a pre-existing relationship with someone near whatever role you're trying to move into.

" 9-12 months with no gaps in between jobs--in reality, this means "it doesn't look like you were fired"--switching jobs not only makes you look more motivated, it also gives you a wider breadth of experience to draw from."

Fuck HR. 12 months is nothing for actual deep learning. I've seen job hoppers come through my company and it's obvious most of them don't get very deep in the work and just move on instead of becoming a real expert in the system. It's one thing not to hold it against them, but it's something else to say count it as an advantage at such short intervals.

For general software engineering roles, like senior and below, 12 months is plenty of time. Good employees, in my experience, can reach full productivity in ~3 months as long as the company isn't a total mess. This isn't to say they're total experts and know all they need to know about the technology/domain/etc., but it's enough time to pick up what's needed to be a productive contributor.

Eh, I haven't seen it. Maybe my company is a mess. Usually they think they know what they’re doing and can contribute on delivering individual tasks. But it seems they lack the background on the strategy, business acumen, and reasoning behind the technical architecture. So yeah, they're productive in the role, but they probably haven't learned enough of value to significantly grow and bring thought leadership to their next role. Especially regarding longterm implementations of their designs/actions since theyre just onto the next thing.

as an EM, 12mo is too short and I will pass them if i see 3+ of those in their career (say 10yrs). why would I spend my resources to train you for a couple of months and you leave me in another 6-8mo. it will take a senior dev at least 3-4mo to be fully productive. In your example, you are effectively doing a temporary hire for 6-8mo.

I can't imagine it would be too much, depending on how it's worded it could show that the applicant has a 'wide range of experience'. Plus I kind of wonder if HR would already take that into account, it's not just software engineers and salespeople doing it, it's everyone, HR and Execs included

I think big companies (with recruiters) no, they just want to hire people and keep their jobs. At smaller companies, where non-recruiters are screening resumes, I think yes, but only if it's extreme (like 2+ jobs per year for several years).