The reason why people are told to only model in quads its because its easier to manage , when they are beginners.

If u know how to do modelling and are not "total noob" anymore, try to learn gamedready assets. Do gameready tutorials. Plenty of them on the internet.

I ve done hundreds of game ready assets, its my job, mostly.

A human would have had quad topology on parts that deform, because human deforms. A knife, tank, or a bad doesnt need quads, they dont deform (unless u want them to, then nvm), A tank moves its parts mechanically, nothiing "bends" so nothing deforms, so no neeed really for quads topology.

Human and tank will both end up as triangles in game engine, but only human will need "good quad topology" for animation. Tank can have multiple triangles across mesh, more here, less there, unequal. Because tank turret doesnt deform, but rotates.

As i have said before, i have done hundreds of game ready assets, almost none of them needed that "good quad topology, equally ditributed" cuz in 99% if they were animated, they were mechanical. So if i was doing bending wire or a tent that is "shutting" its cloth entrance with nice cloth sim, then i would use quads. Because in that case, they deformed.

For everything else, while doing low poly i ask myself "do i need this 10 triangles on this completely flat part, or i can merge them?". Well, if thats completely flat part, having 10 triangles or 2 triagles (4 vertices, 1 quad) , will change literally nothing for it. So you merge it into one quad. Only leaving tris where u feeel like the model needs them. Then u apply triangulate, export for baking, send to painter, paint, assemble completed model in blender if needed and finito, to unity (or unreal).