Twitter – Some images show automatically on the Twitter timeline, others do not

I would say yes you do receive them all.

Certain replies unless you follow both users are not able to be seen.

Cases for replies and mentions :

1. Your account is protected mentions sent to people who aren't following you will not be seen.
2. You will only see replies in your home time line if you are following both the sender and recipient of the tweet
3. You will see mentions not replies in your timeline as long as you are following the sender

Even during the heaviest traffic times in World Cup I was able to see all the user tweets. The home timeline only receives 20 tweets without the refresh using the more button or the "N new tweets" message. That way it might seem to someone that they are not receiving all the tweets.

For example if X users > 20 posted at 2:30 pm during a World Cup game , it would appear to you that person Y's tweet is missing. It is there , it is just that the timeline only displays 20.

To verify this , you can test with the following tabs open on your browser.

• http://twitter.com/home
• http://snapbird.org/ (Search your friends' tweets and blank for the search term)
• http://api.twitter.com/1/statuses/home_timeline.xml (Inspect in web developer mode using your firefox or chrome browser)

Looking at these three will tell you that you are in fact getting all your tweets.

Edit

If you inspect a user's timeline and are sure that it does not match up with the three above then I would suggest to check http://status.twitter.com/ to see the current status of any errors that are occurring site-wide.

If you think it is more localized you can submit a Twicket : http://help.twitter.com/requests/new

Think your Twicket is taking too long shoot a mention to @delbius the lead on Twitter's Trust and Safety team.

Because the tweet in your example is not a reply (note that it doesn't show the tweet they're replying to). A tweet is considered a reply when you click the "reply" function in the website or a Twitter client. This sets the in_reply_to_status_id parameter of the tweet, which is how Twitter knows it's a reply to a specific tweet. If you simply begin typing, even if there's a @username right at the start, the in_reply_to_status_id parameter is not set, so Twitter doesn't consider it a reply and people who follow you will see the tweet even if they don't follow @username.

I hope that clears things up.