Free Trial's aren't PLG

To begin, let's define our terms.

Freemium: Offer free value of the product. Typically resource constrained, feature constrained, or seat constrained. Unbounded by time. You can have it free forever if you stay within the sandbox.

Free Trial: Time bound access to all or most of a SaaS product.

In Freemium your goals are to create active product users over a longer period of time. Give them repeat product value, and then convert them to paying customers via (ideally) a self-serve upgrade flow. (1)

In Free Trial your goals are to create active product users in a condensed period of time. They typically already have a project scoped or a more honed expectation of your product. They’re coming to you most likely in the “consideration” phase of their buying journey.

You can have both (ie a reverse Free Trial). But if you don’t start with Freemium first, it’s likely you’ll never do it. Or you’ll try and do it and fail. Because a top down sales led go to market motion is completely different than a PLG-first, freemium product experience. It’s not a matter of flipping a switch. It will take time, and initial results should focus on growth of the signups and repeat usage, not monetization or expansion.

In B2B SaaS products that are a bit more complicated, a Free Trial is essentially an extended proof of concept (POC). It most likely will have a white glove service element - since they can’t get product value without some help from a technical team member or by taking some concrete action with your SaaS product (ie connecting their production AWS environment to a cloud security SaaS vendor without going through security approvals). (2)

In this scenario, you will have a slight leg up from the competition that do not offer Free Trials: you get in to the account easier and earlier (you dont want to be the last vendor invited to a POC process) and you realistically can have a technical practitioner get accustomed to the product a bit and be an advocate for you. In my opinion this is not PLG. It’s the bare minimum of getting technical people some product exposure but your GTM motion is 90% focused on top down sales. (3)

Free Trials don’t generate pipe, the best you can hope for is that it accelerates sales cycles by engaging already interested buyers.

So if you do a Free Trial in B2B SaaS, your focus should be on acquiring leads with high intent, and measuring the success of your Free Trial flow by comparing velocity and closed-won conversions to the non Free Trial funnel or your historical funnel metrics.

1. In B2B SaaS this is a land and expand approach. Account Executives should be incentivized on the expansion of the account as they scale and need more Enterprise features. Mark Reborge's talk at SaaStr touches on this and much more.  
2. In the cloud security space, it’s unlikely you’ll find an end user practitioner ambitious enough and empowered enough to connect their cloud account for a Free Trial. If they do, it will likely be a much longer Free Trial and you’ll need to extend them several times. OR they will just kick the tires and you will spend months chasing them.
3. Gartner calls this "Sales Led Growth" or SLG. For SLG to be successful, you still need to have a delightful user experience, clearly communicated and defined tiered packaging, and frictionless expansion. Which raises the question, if you're going to invest in that, why not go all the way in a freemium PLG?