Granting execute rights to all stored procedures used to be a cumbersome problem up to before SQL Server 2005. You  either had to give elevated rights to the user or run a script to GRANT EXECUTE on every stored procedure.

 I still see plenty of databases where a DBA has granted db_owner rights , simply to allow stored procedures use.

There is now a more elegant solution , using ROLES. Which also have the added advantage of complying with security best practises , and many corporate security policies I’ve read.

-- create database role
CREATE ROLE db_execute

-- grant EXECUTE permission to database role db_execute

GRANT EXECUTE TO db_execute

 -- add database user account to the role

exec sp_addrolemember 'db_execute', 'database_user_acct'

An alternative is to  use schemas and apply execute on the schema

 e.g

 GRANT EXECUTE on myschema TO [myuseracct]

 Be careful , in applying these roles – as you may allow access to functions or stored procedures , which are developed in the future. Adding this role to the database user will allow all future stored procedures to be accessed.