:The fillets do more than add stiffness. They distribute the stress and avoid stress risers. They also allow you to lay the glass smoothly over the joint.If you doubt me, Run an experiment and build up a couple of test pieces. All stitch and glue sources show fillets. Without them the glass will crack and tear at the joint.:

rob macks talks about ways of using hot glue between the forms to slightly hold strips together when gluing up. joe greenley uses hot glue tabs on the inside seam 'tape' to hold it in place before easily wetting out.

i was just thinking about combining these 2 approaches and applying to s&g. the tabs hold both glass and the yak together a bit while laying in the resin. if the cloth is very narrow, it could be sorta thought of as a fillet but is stronger. i bet there are times where the inside is not so bevelled that this little tab approach would help, so the idea is to use it for 2 reasons. but idea only don't know.

but if the yak gets thinned out here by rounding, more glass would be needed to get the separation desired so the filled fillet approach may be best in this situation.

maybe nylon or polyester would be good for the 'fillet cloth' in that you get a flexible core to help in major impacts. glass cracks and breaks, but panels stay together. inside visibility tho, anyway if glass would be more transparent than filler unless micro balloons

sounds like not worth the hassle unless one had a specific reasons to.