Lasix

Question I have:

Is Lasix used extensively on horses that have not bled or have bled what might be considered insignficant amounts ? (I guess insignificant would mean no breathing problems or infections likely, etc... because the amount of bleeding is so small).

Once a horse bleeds, its Lasix for life, if the trainer so chooses?
I also know that in Texas anyway, a horse can get on lasix if bleeding occurs
during a workout which makes sense. But the vets have to have a look.