On both Adobe Sign editions (Business/Enterprise) version the number signers per transaction is 25. However, in the Enterprise version it is possible request increase, by opening a ticket in Admin Console (tip).
Some cases in Brazil, have documents that have signer more than 25 signers per transactions needs. example: meeting minutes, class attendance list, petitions, agreements with employees.
Suggestion: Adobe could increase the max number of signers per transaction: but these users can place initials/visas (valid for knowledge about content and not necessary legal consent, such as a signature).
This would expand the use cases without having to contact the Support Admin.
Benefit to the user and not decreases consumer transactions by service users.