TimedRotatingFileHandler not working for minute intervals

Question

I have configured a couple of TimedRotatingFileHandlers like this.

[loggers]
keys=root

[handlers]
keys=logfile, logfile_errors

[formatters]
keys=logfileformatter

[logger_root]
level=DEBUG
handlers=logfile, logfile_errors

[formatter_logfileformatter]
format=%(asctime)s %(name)-12s: %(levelname)s %(message)s

[handler_logfile]
class=handlers.TimedRotatingFileHandler
level=DEBUG
args=('./logs/log.out','S', 1, 10)
formatter=logfileformatter

[handler_logfile_errors]
class=handlers.TimedRotatingFileHandler
level=ERROR
args=('./logs/errors/log.out','M', 1, 10)
formatter=logfileformatter

However, when I log something like this in different minutes

logging.error('MY ERROR')

Backup files (1 per second) are created for the logfile handler but not for the logfile_errors handler (I would expect one backup file per minute in which an error was logged). Am I doing something wrong when configuring the handlers?