When to scrap an idea?

Hi everyone,

As this community is all about product ideas, I'm interested in your opinions about when to scrap an idea?

I mean, everyone has product ideas and the next step is naturally to do a market research if a similar product already exists, competition, audience etc.

I did that not long ago for three ideas I had. And for each idea I discovered a different reason to exit.

idea #1
An app which allows me to track long-term traveling across multiple cities or countries. The idea was to provide an app internal timeline to share with friend & family but also to automatically post new pictures to Twitter, IG, FB etc.
Reason to exit: The market leader (www.polarsteps.com) has a great product (which I actually use now .. lol) and about (self reported) 3 million users.

idea #2
Enrich stock information with a sentiment analysis of news. You would basically search for your desired stock and a smiley would show you if the news around that company are either negative, neutral or positive. You could use that information to asses your decision to buy, sell or hold.
Reason to exit: This is not a product. It is merely an additional information that a stock investor uses among others to make a decision.

idea #3
A web app that allows entrepreneurs to create Google Ads & a landing page in a easy manner. To create a Google Ad & a landingpage is super painful learning curve increases drastically. Everyone who is new to that might becomes discouraged very easily. The user could select Ad templates, landingpage templates, keyword help etc.
Reason to exit: I don't have marketing/advertisement domain knowledge, competitor exists (www.wordstream.com)

Or, maybe, an interesting information would be: How (often) did you re-shape your product until it was worth to give a shot?