on apc.h the quick, incomplete,  example is (line 315)

if ( 
 !wrapper->wops->url_stat_interval > 
 apc_time()- time_since_last){
            return -1;
}

Would need : 
-a config variable set up for url_stat_variable. 
(package xml update, loading, etc)
- a persistent variable to keep the last stat time

Perhaps taking this a step farther, would be to allow an apc_*() function to mark the current file stat cache as "dirty".  So instead of re-stating all files at some interval, it would stat the file when it caches the opcode; later at some point you could call some function (say apc_clear_cache('stat')), and that tells APC "from this point on, don't trust current stat data -- instead, restat the files and recache the new file stat data, evicting the opcode cache if the new file stat shows the file has been modified"

The problem with the stat interval is that if limits you to only receiving updates to the files within "n" minutes/seconds.  But currently the only way to update files in cache when stat is disabled, is by calling apc_clear_cache('system'), which forces *all* opcode entries to be removed.  If you're only modifying a handful of files, that makes the full cache clear unnecessary.

i recently wrote a feature request and even suggested "apc.stat_interval" while submit notified me about this existing one 

so +1

it would make a HUGE difference under high load even if you set to a low value like "apc.stat_interval = 5" in cases where you have many parallel requests per second 

* overall load would go down
* small bug fixes in scripts would get active in a accetable timeline
* you would not need to reset ALL opcode chaches

You can try this hack in lazy_stat.patch

apc.stat should be set to 0

set apc.lazy_stat_interval to the desired update timeout in seconds (default 30)

APC is no longer supported in favor of opcache that comes bundled with PHP, if you wish to use the user cache, then look at PECL/APCu.