Smart bidding might not be suitable for budgets under $5K per month on Google Ads due to several reasons:

1. Conversions Requirement: Smart bidding relies on having enough conversions to be effective. With a limited budget, you may not get enough clicks or views to generate the necessary conversions, making smart bidding less effective.

2. Customer Value Knowledge: If your ad spend is low, it's possible that you haven't determined the value of your customers yet. Without this information, it's challenging to set a value to guide Google's smart bidding algorithm.

3. Data Limitations in Privacy-First Era: With increasing privacy regulations, the amount of data available is decreasing. For example, to use customer match lists to exclude existing customers, you need consent from at least 1000 individuals, which might not be feasible with a smaller budget.

For low-budget Google Ads campaigns, alternative bidding strategies include:

• Max Clicks with a Bid Cap: This strategy aims to maximize the number of clicks within a set budget. A bid cap is used to control costs, often set at 10% of the daily budget to ensure at least 10 clicks can be afforded.

• Target Impression Share with a Bid Cap: This strategy helps you understand auction prices and assess if your keywords or targets are within your budget. It focuses on achieving a certain share of impressions for your ads, with a bid cap to manage spending.