I have a question, specifically directed toward models who schedule on at last a part time (if not full time basis).  Why is is relatively rare for models to post calendars of their availability? It seems like it would be timesaver for everyone involved. There are some low cost apps that are fairly flexible and even a google calendar for basic needs.

"...Why is is relatively rare for models to post calendars of their availability? It seems like it would be timesaver for everyone involved..." 

"Be the change you wish to see in the world." Mahatma Gandhi

Bod carpe diem!  Please do consider taking the lead here...

btw, this is actually a relic of days long past... a decade ago MM actually had many folks (including myself) who would post there availability.  In fact I still do... check my profile...

Once again BE THE CHANGE YOU WISH TO SEE IN THE WORLD Bob...
enough said.

Probably because modeling is not like a convenience store.

Back when I was a traveling nude model, earning most of my livelihood that way, I posted upcoming trips on my profile. I would detail what days and times were available and which ones were booked. I did that for close to a decade, but people rarely looked at it. Plus, due to the way searches work on this site, it was rare for someone in a particular area to see that calendar posted at exactly the right time to book it. I still had to spend 2-4 hours daily, reaching out to photographers in specific cities and "cold calling." Cold calling was non-stop, regardless of where you posted availability or how picky you were with updating it. Ultimately, I made a living off of searching people in certain areas and reaching out to them, not just posting availability on MM and social media. Almost no one saw it there. I did successfully use Instagram to schedule shoots from about 2017, until I finally quit shooting in fall of 2019. I made travel schedule posts there, which were slightly more effective than posting them on MM, but I had to create extremely bright and eye-catching ads for followers to notice. I'd spend 2 hours making the image to post, designing it all in PhotoShop, then perfectly placing the calendar part around the eye catching image. Sometimes that would get me a bite from someone, making it worth my time. Often, it would not. It was always a crap shoot.

Came here hoping to learn what caldenars are. Disappointed.

Aw, hell no!
So much wrong with this, beginning with safety concerns, and ending with being booked for 2 hours and photographer insists you stay longer for free since he can see you aren't booked later that same day. Or insisting you go to lunch/dinner with him since you have free time. No. Just no.