I've never even HEARD of a 10-day conference before. Most conferences I've seen are two-days with an optional third, broken up as:
1. Optional "workshop" add-on day, preceding the main conference. Basically a guided tour through writing a Hello World app in Spring Boot, or React, or whatever framework is hot that year.
2. The main conference. Two days of hour-long sessions, with speakers consisting of:
(a) consultants trying to promote their firms,
(b) "evangelists" trying to promote their company's products, or
(c) local devs who don't require travel expenses, and are just presenting a topic to pad their resumes.
Around 90% of the value I've received from technical conferences came from group 2(c), and I'm not sure that was enough to justify the whole.
What the author describes sounds more like "a training class", which is a different animal. Even then, I've never seen a training course longer than 5 days.