The more Tweets the better maybe?
Should it be volume over quality? Volume over time of day / day of week? Who should be seeing your tweets and will a million followers mean that your tweets will be guaranteed return on investment?
Once you have an active presence on Twitter you need to fully understand your target audience and their behaviour. It is important to remember that users are active on twitter every second of everyday, an estimated 500 million tweets take place every day so it is vital that what you have to say does not simply get lost in someone’s time line.
The amount of tweets a day you should be posting is really down to the type of business you have, some are B to C and others B to B, some to a very target audience and some to most of the general public. When do they people who you are trying to target view their tweets, when are they interacting with brands and what are the common hastags or keywords that are being used?
If you can research (social media management softwares will help) what effect your current tweets are having with traffic to your website you will have a better chance to really home in on the best time to tweet and the frequency / keywords you must be delivering. Reports show how well each tweet as done and if they were shared / retweeted or obtained a click through.
Some Twitter users have a very specific audience they want to target and it is even known that some will wait for their target person to tweet on Twitter and immediately tweet to them thinking that at that precise moment they are viewing their updates and likely to see their tweet. Others create lists of accounts they want to target and communicate individually with each upon the theme of their latest tweets ~ This for many works well.
How many tweets should you be doing per day? You should be really considering more important points such as who, where and when your target audience are active on Twitter, the topics they like to discuss and they way in which they talk ~ ie Abbreviations may work well for the younger generation, but not so good for those older… Once you understand your key target audience then you will know how many tweets a day it takes to engage with them.