It's not just being lazy and waiting.  Those can be handled.  But why are all the difficult ones always at the end?  I

I have $200,000 of home improvements to reduce my gain.  Do you have documentation and is it exactly $200,000?  Somewhere.  Can you get it?  I'm going on a fishing trip this weekend.  The deadline is next Tuesday and today is only Tuesday. Okay, just go with my $200,000.  Oy,.

They're all big dollar issues that you cannot just ignore and file an extension on.  You need the information for them to pay.