Is there a limit to total number of CAPTCHA tries? Is same proxy used for all tries?

I know some systems have a limit and will lock out a user after x CAPTCHA fails.
But…I also know that this might only affect things if one proxy is used for consecutive solve attempts on fails. Which way does SER handle consecutive solve attempts: same proxy or different?
AND, if same proxy is used, what’s the highest number of total tries suggested?  I have used various external solvers, and even the ones at the end of the list seem to get used, so it seems having a high number of tries does work.