There are authority sites that are very well known and they do not always practice good Google Panda and SEO principles. In this case, these sites will be very well organized and crafted, but they have very little copy on the pages. Some have way less than 400 words but otherwise the page looks great. This is in direct conflict with what Google Panda is all about which is eliminating poor quality sites. The reason many of these pages are still ranked well is that they ranked well a long time ago. Probably Google does not immediately deem them to be a high priority target.
Experienced webmasters would never make the mistake of using the same Title Tag on more than one page. But it is seen around the web, and you need to be aware of this mistake if you are new. Of course this is something that will not sit very well in some aspects with Google. The danger here is you may be judged as having Internal duplicate content. If you place the same title tag on more than one page, then unless its a mistake you are doing it for a reason. The two pages will be about the same topic and there is the possibility of incurring a penalty. So always remember that every page must have a unique title tag.
Failing to specify the Alt tag for an image will not get you a penalty from Google but it is poor SEO practice. SEO service in Singapore explains some IM marketers try to game a little by stuffing the Alt tag with keywords. That is just a very bad idea and it will cost you to some extent and how much is unknown. But it will be seen as keyword stuffing, and you should know by now that keyword stuffing is a no-no. So just add a very short description in the Alt tag and then the search engine bots will be able to identify and know what that image is all about.
There are legitimate reasons for the Google Panda update and the new line of mistakes people can make. However, you may be experiencing the pangs of weighing if it is worth it or not. It really just all depends on your situation and what you think is worth it.