Only certain number of items per cron run

I've done a lot of testing. For example I've created 20 contacts in Salesforce and started the cron. It took a long time and in the end I've got an script error (500). I think no matter what kind of item will be imported from Salesforce we should restrict the number of items which are imported each cron run. I think eojthebrave restricted the number of items to 10 (in his salesforce account module). What do you think?