How often should I visit my Mom in assisted living?

It's a skill to learn how to leave. When I get to the facility (before I go in), I set my phone's alarm for 30 mins and 45 mins. When it goes off, I end the conversation because I have to run. I usually say something about my kids' activities are calling. If I'm talking to the nurse in charge of her care, I'll go to the 45 min alarm and will leave right away. This structure forces me to stick to my plan and not be overcome with guilt. My now means now, not in a few hours. It also shows I have a life outside of visiting the Nh.

My mother lives in an upscale independent facility.
The facility offers 3 meals a day, many different social activities and a shuttle service to anywhere she needs to go.
My twin sister and I live fairly close to the facility but we both work full time. We feel like we’re being pulled in so many directions with work, family life and seeing our mom.
We feel like we’re at our moms beck and call and even though she has several activities a day to choose from, she relies on us for her entertainment.
We love our mom dearly and would like to know what is expected out of us in visiting her.
We are both feeling guilted into seeing her way more than we have time for right now.
Any insight would be greatly appreciated! Thank you

Beatty, time for you to stop being Julie McCoy, Cruise Director. Your Mom isn't joining activities because she knows that you and your sister will be popping in at a certain time, so she doesn't want to miss you.

You and your sister figure out a schedule. Visit just on the weekends. You take Saturday mornings or afternoons for an hour... and your sister take Sunday, or vise versa. Or choose another day during the week. Fuss over her by saying Saturday [or Sunday] will be our time :)

Does the facility offer physical therapy? My Dad use to go to physical therapy every other day, so that was an "activity" he looked forward to going. After lunch he would doze off.