I had two interviews during the last two weeks, one of them was about 30 minutes, and they had me fill out a job application before it, and the other one was less than 10 minutes!
In your own point of view, how much time do you need to interview a .NET developer with almost 2 years experience?
I like to do the following:
I like to interview a minimum of 3 candidates, after reviewing at least 10 or 20 CV's.
Once you get past that point, a trial period is mandatory, this is normally a month or so.
Both of your interviews sound far too quick to be proper interviews, you werre probably just a 'filler' interview, unfortunately for you.
It depends how quickly they can demonstrate that they're not good enough for the job... ;-)
Perhaps a better question is, "how long does it take to fully assess someone's technical skills?" Unfortunately, the answer is always going to be "longer than the length of a job interview". Interviews are supposed to provide as much information about the candidate to the interviewer in as short a time frame as possible. It's hard to judge that quickly or accurately, and the only real measure they'll have of your skill is how you perform once you already have the job.
That said, 10 minutes is much too short to conduct a proper interview. I'd recommend writing back and expressing your concern that this wasn't sufficient to demonstrate your skill set.
It depends on the level of the candidate.
If it's for a regular developer job, 20 minutes is enough to test basic knowledge about a given programming environment and language (talking .Net here). I don't mean going into the depths of each aspect of a language, but a simple set of questions from which you can conclude on what level the candidate is.
Higher level developers and architects require more time to let them explain certain decisions they've made in their current/previous job.
The interviewer's mind is typically made up in the first ten minutes, the rest of the time is just spent trying to justify that decision.
This is especially true if there is a technical test which has already been marked in advance.
I doubt that the amount of time that people should spend on interviewing a developer is dependent on technology.
My expectation would be that a proper interview process would take several hours minimum, roughly split into the following parts:
Overall, I would say that a company that is careful who they hire will spend at least two hours interviewing the candidate, plus one or more phone interviews. Some companies go way above that (Google, for example) but I found the above a good rough guide both as a candidate and as a manager who was hiring as to what the minimum interview process should look like. Sometimes it is obvious that you can cut part of the process short either because the candidate just isn't very good or because they're so obviously brilliant that digging deeper might be unnecessary. But the latter category usually has the technical interview running way over time simply because it turned into such an interesting discussion.
These days I am very wary of companies that don't seem to bother investing a lot of time into interviewing a candidate - would you really want to work for a company that spends 10 minutes screening just about anybody with a pulse before making a hiring decision?
I don't think an interview of more than one hour is necessary for the average web development position. I should know before the candidate arrives what my must-haves and can't-stands are for the position. If I'm going to keep someone in my office for more than an hour I better be ready to pay him for his time. The interview should be an opportunity for me to become convinced this person is the right one for the job. I shouldn't be left wondering. If I am, after an hour, then they're prolly not the right one.
I can usually tell within 15 minutes whether the person will be a good fit for my department. After 45 minutes I'm convinced. A technical aptitude test can be given but it shouldn't be more than a handful of questions. Having a trial period, imho, is crucial but I think 3 months is optimal time. It gives them enough time to settle in and you can then determine whether they'll get off the launching pad or not.
I'm not sure what happened in your case, obviously, but 10 minutes is often all it takes to know that you don't want to hire someone. It could be that these were just screener interviews, and if they liked you then you'd get the more detailed technical interview. If they offered you a position after a 10 minute interview, I say run like hell.
Ultimately the interview should be long enough to determine a few things about a person:
Is their personality a good match for the team?
Are they good problem solvers?
Is there an obvious disparity between their resume and their actual level of expertise?
Usually 90-120 minutes is enough for me to accept someone, could be much shorter to reject.