Darryl’s Analysis

Environment:
Even if the sun shines directly onto the plant for 2 hours, the rest of the time, the INDIRECT light times of the day will be very weak from that distance from the window.  The best thing to do would be to move the plant as close to the window as possible: maximize the ANGLE OF VIEW of the overall sky, then if the sun shines directly on the plant for longer than 2 or 3 hours, then block it with a white sheer curtain.

Effort:
Don’t water based on a schedule.  Here’s a better approach to watering: (determining WHEN to water a staghorn fern) whenever the soil is about halfway dry (they can even tolerate completely dry soil).  HOW to water: fully soak the soil, letting excess drain away (which you are doing).

The plant will not grow very well in the long term without fertilizer – more info on fertilizers here.

Expectations:
The shield frond of a staghorn fern will always be damaged during repotting or mounting, which is why if you ensure the growing conditions are good (good light) and you’re watering/fertilizing accordingly, the new shield fronds will keep growing.  Same goes for antler fronds – they continually die and as new ones grow.  Trust me, I’ve gone through many rounds of shield and antler frond turnover – this is my plant over 5 years:

My online course teaches you a smarter approach to houseplant care that allows you to enjoy the process instead of worrying about every little thing – and your plants will live their best lives!