nah usually you are right 30 seconds are enough to beat most players. But i often had single positions where white had a position that was + 2.5 in the beginning because of the material value and after felt 20 minutes( i didnt look at the watch) it was 0.0 later i read from someone who had analyst it deeper it turned very much in the minus. That is only for a single position.
Sure there might be positions were 30 seconds are enough.
not to mention that you need an eternity to wait to get a half way decent computer analysis.
It depends, I guess. If you sit and watch an engine hash for ten minutes, you'll usually (not always) find that the moves it first examines are usually the moves it ends up with. That said, I think a 30 second computer search is probably far beyond the skill level of most players. (If not, then you should be able to beat any computer engine by limiting it to 30 seconds of search time.)
There are two solutions, both of which I use. You can turn your back on the computer and do your own analysis while the computer is hashing. Or if you have Fritz (or another UCI with the capability) you can let it run overnight on whatever game(s) you like and get up the next day and use the in-depth analysis of hours of searching.
My guess is that for most of the time, you will find the same moves after 30 seconds that you will after 8 hours. Either way works for me because I'm not good enough to understand 8 hours worth of analysis on a single position, and the nuances are likely to be so small that I am unable to take advantage of the differences if any.