I look at it every day or every few days. I also do a lot of reading/research. But I'm not doing index investing either, so I have a good reason to keep an eye on the market and certain stocks. If I was an index investor and had, say, a three fund portfolio, I probably wouldn't check it nearly as often.
I'm similar to this, maybe checking a little more frequently. It is very uncommon for me to go a day without having my portfolio open and refreshed frequently. I haven't noticed any wealth effect. I am in a lot of growth stocks, so I know that the numbers that I have right now could fade away very quickly. I somewhat view it as a potential wealth indicator since I am up quite a lot at the moment. When I have up days, it definitely makes me happy, and when I have down days, I like to look at which stocks drove it down and see if there is a reason or if it is just due to market fluctuation. The majority of the time, it is due to market fluctuation which causes me no concern because I am confident it will come back. In addition, on those down days, any of my stocks that moved up, I see as being a huge success because they beat the market significantly and will likely rise when the market does. Then when the stocks that were down level out, I will be ahead. May be some weird rationalization, but it has actualized that way for me many times.
I also get some good buying opportunities like this. One example was a month ago when one of my positions, DDD, fell by 30% on an earnings warning. Looking at the release, it was due to high r&d and acquisitions costs, and they actually expected higher revenues than before. To me this was great news because I want my growth company completely focused on capturing that growth and growing revenues. You don't own a stock like DDD for earnings right now. I bought some that day and that's now up 30% in a month, it was a clear overreaction. That being said, with a stock like DDD, any day could lead to another 30% drop.
Doing this doesn't give me any reason to sell. I usually buy a stock intending to hold at least a year, so until that year is up I don't really consider it. For example I have some JCP (damn) that I bought at a cost of $18.11. It was down about 70% recently, but I'm definitely not selling it at that point. I've pretty much written it off as going to 0 and if I eventually get it back, then it's a nice bonus. The last few days it's risen about 40%, so while I'm still way down, maybe after a year I will be close to even.
Either way, I still eat my pb&j and water for lunch.