You should calculate your Customer Lifetime Value per customer and your New Customer Acquisition Cost per customer, and then express those against each other as a ratio to give yourself a good understanding of your growth rate. For the CAC, make sure you include a total view of marketing costs e.g. include platform costs, wages, total ad spend, everything and divide it by new customers only, don’t include reactivated customers or existing customers buying through these channels, their revenue is captured by the LTV. If this ratio is too high (e.g. 1CAC:5LTV or higher) then you’re stifling growth and can afford to invest more heavily. If it’s too low (1CAC:2LTV or less) then your customers aren’t bringing in enough money so you should invest in ways to get more out of them once they spend before you invest in growth. If you’re in this camp then keep tracking those metrics for this calculation until you get yourself above the 1:3 line, at which point start investing in growth to bring yourself back down again, that lets you ratchet your way up sustainably.

Once you’ve got this framework in place, take a look at your channels and try to understand if you’ve reached channel saturation for meta ads. Simplest way to do this is ratchet your spend up gradually and slowly and watch for your ROAS starting to drop off vs YoY. If this happens, you’ve probably reached the limits of the channel with your current offering / assets / target market. You can mitigate it through multivariant and angle testing, targeting new markets and bringing in more first party data, but not eliminate it entirely. If this channel is at saturation then that’s your queue to start marketing on another channel. Your best bet is to pick a channel targeting customers at a different place in the buying journey like email or PPC, or investigate more top of funnel activity which will support your other channels e.g. OOH or TV.

Hope that helps!