When projects have long acceptance tests periods due to dismal code quality and when there are never enough testers in the team to get the work done you almost have no other choice then to alleviate your testing bottlenecks as follows:
- Have developers to do the work of testers instead. Not very popular but extremely efficient. Priority is given to the old stuff to migrate in production before developing the new stuff.
- Implement testing tools and scripts to ease testing.
- Automate tests.
- Continuously improve testing processes.
- Build a Test Craftsmanship Community within your organization.
- Hire more testers.
To make a long story short: build less but build it stable!