When I hit the "I allowed one month for interviewing and one month for buffer", I already knew what the outcome would be and my brain was screaming "WRONG!"
Job applications are very stop-start affairs. Post a job ad. Wait a couple of weeks for it to finish. Then leave the collated resumes on the hiring manager's desk for a while, then someone prods the manager "why don't we have a -foo- yet?". Manager starts the callaround, does the first round of interviews, makes a shortlist, then they sit on the desk again. Maybe discuss potentials with other staff, but it peters out. There's so much other stuff to do! Then someone says "Why don't we have a -foo- yet?". Rinse, repeat. It certainly doesn't always happen, but it's common enough.
At one place I worked, I was basically the sole applicant - my friend worked the other support role and recommended me. The HR officer (CEO's wife...) called me in. That went well, so I had a second 'confirm this guy isn't an idiot' interview with the CEO. A couple of polite proddings received no response. I asked my friend and he said "I thought we did agree to hire you, that's what I heard". A couple more proddings and the CEO said 'Yes'. But the HR officer wasn't responding. At this stage it was six weeks from first interview to CEO 'Yes'. We hadn't even discussed salary yet. I was so desperate for a job at the time, that I just rolled up and started working, because fuck it, the worst that can happen is that it's abysmally low and I go elsewhere - it's not like my days were productive otherwise. A panicked call from the HR officer the next day did a hurried salary negotiation.
Now sure, the last part of this story isn't typical (though I find it funny), but it took 6 weeks for me to get a job with a small, busy company who had staff with prior positive experience with me as a colleague and no competition. One month is nothing when it comes to applying for skilled work.