I believe that your friend is completely right!  I try to avoid participating in bounty companies that go more than 8 weeks ...
If the company carries the main stage of ISO, this is very bad ... So the money on the presale is extremely low, and it is unlikely that this project will collect softcap  
But there are always exceptions to the rules.  

Yes because more and more bounty hunters are registering in a time. So there are more stakes but tokens allocation is fixed. That is why you earn less in long lasting campaign.

It's usually happens to me too, if I saw so many people on the spreadsheet before joining a bounty campaigns, I'll rather not join or if they extended the duration of the campaign,
All this allows for more work without adding more rewards.

Well, it's not a fixed rule, but usually the winning bounties do not postpone closing. Usually, if a campaign gets too long it means that sales are not going well.

Personally I don't like to follow the bounty with long period of time,I get bored quickly and like to try many of the project's bounty with the term turbo bounty and is usually much there in the bountyguru.To how much token will we get I think depend in rank,the number of participants and also number of supply.

Logically, of course, yes, because the payback must take into account the average for one day! But there are promising campaigns that ICO conducts for 6 months.

This can happen with the stake system, but other systems are not affected from the length of the campaign.

There are many interesting projects to check out and others not, so it's important to choose wisely.

Looking at the project as a whole and looking at the team behind it, is very important to make a correct decision.

If I can give you guys my opinion, I discovered an exciting ICO that is very interesting: RAWG.

Check out this new article where RAWG is mentioned as the "IMDB of gaming" on FORBES, one of the leading global media company, focused on business, investing, technology, entrepreneurship, and leadership.

https://www.forbes.com/sites/andrewrossow/2018/07/16/3-reasons-the-video-game-industry-is-bound-for-blockchain/#69da81c87810

The ICO will start in a short period and they are at the moment in pre-ICO phase. This is the ICO site: https://token.rawg.io/. It's a video game discovery platform that converts your skills into goods and services (the site is already working, with more than 57,000 games in the database) and, which is very interesting, they have already reached the soft cap.

Have a look and get some information while doing your own research!

Another interesting point: RAWG has already secured $5m USD, halfway to hard cap of $10m!

all depends of the campaigns that you follow. There are also some campaign participants who pay very expensive, it's very profitable. but there is also a long-running but the result does not have a value. We have to be clever-clever choose project, if sales a few weeks no result I suggest switch with project better.

I also think that the longer the bounty task lasts, the less income it has, because the total distribution reward has not changed, but we spent more time getting it! What if I encounter a fraudster?