Very good point here. It should always be kept in mind that we don't want links from pages that already look like link farms or have too many links stuffed in it.

Also if you are the one who visited that page in early days of it. And right now you only see 5 - 10 links then also the possibilities are 190 more can be added to that page. Over here we cannot predict but you can atleast try and only link from the pages which have 5 - 10 links so even if 10% of them are going to be leeched in future you get proper boost from them in future also.

Otherwise someday in some google update you will see your PR is now decreasing.

Thank you very much Jignesh for your advice.

Thank you very much for your information