Tray development is the traditional way for film, and has worked for a century. There are some key insights.
First, scratching a negative with the corner of another is the most common problem, as the emulsion is fragile when wet. So it's best to learn a shuffle method whereby the negatives are face down, with the top negative placed under the stack, keeping all of them parallel so the edges are aligned. This helps to eliminate the scratching problem.
Second, gloved hands are best. Tongs are impossible once the film is wet, the developer makes the film feel slippery and slimy. You have to be able to tell if you've grabbed a single sheet or if several are stuck together.
As for the agitation method, I don't bother with counting how many passes I've made, just use a constant, gentle shuffle method continuously for the duration of the development cycle.
Use a large enough tray, otherwise you can get dense areas parallel to the edges where the wave action bouncing off the tray walls causes localized excessive development from increased agitation.
Due to the temperature difference between your fingers and the chemistry, keeping your fingers in contact with the film too long in one spot can cause density marks, due to accelerated development in those areas.
Besides these cautions and conditions, tray development is very simple, and also meditatively enjoyable. I recommend everyone should try it.
~Joe
