Why t-shirt sizing alone doesn’t cut it for real prioritisation

One of the recurring pain points I've seen in product teams is how easily prioritisation becomes performative. T-shirt sizing feels inclusive – it gives everyone a seat at the table, from engineers to execs. It’s fast, familiar, and non-confrontational. You can throw a bunch of cards on the wall, and it feels like progress. And most of the popular roadmapping tools build around exactly that: a quick estimate of “S, M, L” and off you go.

However, when it comes to actual decision-making, it falls short. Too often, everything ends up as a Medium. Or a mix of Smalls and Larges with no clear sense of which ones deliver real value. It gives the illusion of certainty but doesn’t give you what you need when priorities clash or stakeholders push back.

At my previous company, I tried introducing a more structured method: WSJF (Weighted Shortest Job First). It was a step in the right direction, because it tries to factor in both value (to quite some granularity) and effort. But the reality? It became a time sink. Too many variables to score, too many senior stakeholders to get agreement from, and far too much debate about how to quantify business value. The exercise ended up being scrapped – not because it wasn’t valuable but because it was too slow and too political.

(You can read more about that attempt here: https://lnkd.in/ette25gN)

Some more advanced PMs have tackled this by building incredibly detailed spreadsheets. Business cases, assumptions, estimated ROI, risks, tracking models – it’s impressive but it’s also brittle. These spreadsheets live in silos, need constant manual updates, and rarely feed back cleanly into the roadmapping tools the wider team uses. It’s messy and it’s costing time.

That’s one of the things we’re working on at Product Seed.A way to move beyond vague t-shirt sizes and spreadsheet chaos – towards a smarter, lighter-weight approach that ties product ideas to real business outcomes, helps teams make confident decisions without weeks of scoring sessions, and tracks it beyond the delivery of the feature.

If this resonates, I’d love to hear how your team approaches prioritisation.

And if you want to follow along as we build this, feel free to follow us on LinkedIn or sign up at productseed.com for updates. 

You can also message me directly at Gianna Illenseer if you have any questions, want to discuss, or want to be part of our beta programme.