Comment by technion

That limit of ten is extremely easy to meet when someone casually says "Hey we've started using Freshdesk for ticket tracking, setup DNS please". Ok so you include:email.freshdesk.com. That record itself includes four other freshemail.io DNS lookups, and sendgrid.net, which includes another one. So you're seven DNS lookups in just for that. Gmail's recommended include:_spf.google.com includes four more, at which point the limit is exceeded and SPF is broken.