It's not such a matter of why not use it, as it is that the larger companies get the attention of the audit firms first.  After the audits for larger companies are completed they can pivot to audit the venture companies. 

Some venture companies will indeed file prior to the deadline because they have their act together or their filings are simpler, but also because their auditor makes themselves available earlier.

Remember that audited Q4 must be completed by Apr 30, but then un-audited Q1 must be filed by May 31, so we get six months of data in a 31 day period....So SIGGY,ther a chart on this page shows what the best time might be to average down,if your not in that positon thats fine i know plenty of people that are starting to set ASK LIMIT between @.40-@.60 above SP for the next 90 days,then sit back and don t look for a little while,GL