Can you give us some context or background of the field you’re in? Things differ quite a bit between a mobile app vs shipyard crane controller software.
The point is that even “proper” long term planning doesn’t work for the former. You never have enough information for the plans to actually materialize, it’s not simply the planners fault.
Well ... in my 30+ years I've done medical (imaging and diagnostics where design controls and planning are required by regulation), enterprise firewalls/anti-spam/anti-virus (again, design and planning critical), more than a few mobile apps, SaaS, VR. So pretty much the gamut.
Long term planning "works" everywhere ... you just have different plans: sometimes less detail on the 3-12 month items, sometimes you need a detailed plan out for a full year or more.
The point is that even “proper” long term planning doesn’t work for the former. You never have enough information for the plans to actually materialize, it’s not simply the planners fault.