Agency owners: what is actually costing you money?

I'm doing some research into the biggest operational/sales problems that marketing and lead-gen agencies face.

I'm not selling anything and I'm not looking for generic answers like "getting more clients."

I'm trying to understand the problems that actually have a measurable financial impact.

For example:

- Leads come in but aren't followed up quickly enough

- Leads get lost between different tools/people

- Sales reps forget to follow up

- Qualified leads don't convert

- Proposals/quotes take too long

- Clients don't renew because ROI isn't clear

- Reporting takes too much time

- Client onboarding is too manual

- Something else entirely

If you run an agency, I'd really appreciate some real numbers:

1. What's the biggest problem you've faced?

2. How often does it happen?

3. Can you estimate how much revenue it costs you per month/year?

4. What have you tried to fix it?

5. How much would solving it realistically be worth to your business?

Even rough numbers are useful.

For example:

"We generate ~100 leads/month, but around 20–30 don't get followed up properly. We estimate that costs us ~$X/month."

I'm trying to understand the economics of these problems, not sell a solution.

Thanks — genuinely interested in hearing from people who actually run agencies.