No, branches break down badly when you have many experiments. You end up with a bunch of incompatible versions of the system that you need to merge together lat

No, branches break down badly when you have many experiments. You end up with a bunch of incompatible versions of the system that you need to merge together later which can be a huge mess (depending on the size of the changes). By all means, branches are great for super-prototypey early code, but once you know that you want to keep the ability to run the experiment around, guard it with a flag and merge it into mainline to avoid nightmare merges later!