Lots of coats so you do it once every 2 years. Like 15 coats or more.
I hung my trip pieces with nylon sail thread from the shower curtain. After it dried they required some touch ups, but it was only the width of a thread.
Do not drip
varnish on the tub or tiles, it'll take 6 months to get it off.
Do not sand in your spare bathroom, dust will attach itself to the walls, ceiling, mirror, everything.
I've flicked the sandpaper every 30 seconds or so, and it helps slow the build up, but increases the dust in the air. Wear a mask. Sanding
varnish takes a lot of paper.