At least once every year or two I think it is important to take an interview even though you might not looking be looking at moving.  It ensure your interviewing skills are fresh and that you have not lost touch with reality and became irrelevant outside the current company. 

If you can not get at least one offer letter a year for more than you are currently making then it means either you're vastly over paid, or more than likely your skills have stagnated and you need to kick it up a notch. 

Even beyond just keeping your public speaking skills in shape there are other reasons to stay in the interview process.

Reasons to get interviewed:

Reasons to interview others:

So take a day out of your year to get  interviewed somewhere, it is better to keep these skills sharp while you still have a job vs getting laid off and then blowing the first X number of interviews because you are out of practice.

Reject conventional interviewing wisdom:

One thing I have messed up in the past and I  think many people still mess up today is they believe interviewing with more companies always increases their chances of getting a job.  That is true in a low skill environment when their needs can be meet with the next person that walks through that door and can hold a shovel. 

There is no reason for them to waste time interviewing many to find the best person that can hold a shovel; anyone will do.  In that situation only by being in a lot of places will you have a good chance of being the next resume/person they see after they decide they need someone.

But in a skilled industry they do not want the next person, they want the best person for their money and only by being their #1 pick will you end up with a job.  You need to convince 8 - 10 people that you can not only do the job but you will take work off their plates, not be a drag on the team, can grow with the company, will not leave before the game ships and will be useful on the next project. 

Plus if you're not the last person they interview your impression has to be so good it survive more recent memories about others they have talked to.

In this environment it does you ABSOLUTELY  ZERO good to interview at a lot of places and always be their # 2 or #3 pick.  You are still just as unemployed as the next person that got drunk and did not even show up to the interview...

So do not waste your time mass spamming companies and then coming to these interviews without a full plan to make them believe you are perfect for that job.  If you have no idea what the company really needs given their history and specific details on how you would fill it; you are unlikely to ever be their top pick for the current job. 

If you have not through about what they would likely need in the future given where they are given their past course then it would be harder to convince them of your future worth to the company.

Seriously, your company specific cover letter and resume alone should have all ready have convinced them you can do this job.  The interview itself should just be for them to convince themselves that their first impression was right, you play well with their team and you should be their #1 candidate. 

If your spending your time in the interview figuring out what they do and what they need.  You are now fighting an uphill battle and by the time you figure it out you will not have enough time to convince them of much.  Spend more time researching each spot you apply to and less time doing mass interviews, you will find that you get better offers a lot faster.