I get new pro pics twice a year and if my looks change at all then I post amature or self taken pics ASAP.  
In the past year I've had more gents than ever asking for recent pics, esp selfies.   I just told the latest one that the pics in my ad are from Dec and nothing has changed.   He said a lot of ladies tweet selfies on the regular.    
Ok well a lot of ladies do a lot of things on Twitter that I'm not about to do either so no don't hold your breath waiting for that to happen.

...an accurate representation of what a provider looks like in the now, as the visual is always what first gets my attention.  For some who don't seem to change much with time, photos could be dated and it wouldn't matter.  For others who have changed, such as age related appearance, or weight (up or down), or who who have altered their appearance with body art, or piercings, or hair style or color, then I'd like to see that current representation in the photos displayed in a providers ad or website.  A provider who has website galleries showing her throughout multiple years is always appreciated.  

A mix of recent selfies and pro pix that are no more than a year old.

And I don't mean looking similar too or "squint and you can see the resemblance". I mean exactly like the person who shows up. If I booked a lady with long blonde hair and she shows up with short dark hair, she leaves (or I do). Show up with a new tattoo across you sternum (or anywhere) that wasn't in any of your pictures, it's gong to be a very short date also. I really don't care if the pictures are recent or 10 years old as long as they are an accurate depiction of what you look like NOW. For that matter, I will also not bother reaching out to a lady if I cannot tell from her pictures what her body looks like. You know, the artsy ones where a sheet or robe is loosely covering what might be a firm tummy or a beer belly. I'm sort of partial to the elevator selfies some ladies post on twitter on their way to/from a date.  
I also expect a lady to inform me if her look has changed before we agree to a date/time together.

Recent are always better as the more recent the higher the chances they accurately represent what you look like now.  

Majority of image hosting services remove exif data from images when you upload image via their service.  

... on if she looks pretty much the same as her last set of photos.  

Ideally something current a few months. So ridiculous anymore with some of these people.

great to be transparent. As long the provider makes herself look closely to the pro/selfie photos, and not years and pounds ago in person, I'd gladly fork out the green$.  

I always take photos every 3 months, but I started doing selfies on my new iphone 12. Pro photos are not always needed.

Doesn't matter, as long as the provider that opens the door is the one in the picture that drew me in! So to be clear, as long as she looks the same as in the picture, not just the same person!

Pretty much what I'd say.

I think accuracy and representative photos are more important than recent. For example, the camera angle looking from top down. That usually means the provider is hiding her weight.  Not to be hypocritical, but I would never take a photo flat footed. In photos just makes the provider look 'squat'. Slightly raised or on toes, makes for a good appealing image in my mind - meaning pretty hot. Love the photos of provider leaning against walls on on toes - super hot.

My friend, you sound like you have a photo fetish lol!

I can agree with those, B-P.  If I may add something unrelated, the duck faces have to go.  I’ve been finding it more and more unattractive over the last couple of years.  I’ve seen ads where the provider has 6+ pictures attached and every single picture is a duck face.

I always keep my main ad pics up to date within last 30 days . It gives fresh attention to my ad and there's no chance of misrepresentation. I also post on my ig every other day so you know exactly what your getting, pics with no filter, no makeup, pics with full make up, hair up, hair down, like yup, you know it's me.  

Within the last three months.  

Within the last few years unless you've had a major body change. Something like breast implants or reductions. Not including hair because that can change often. If you're doing it twice a year that feels more than recent enough for me.

A person can change considerably in 2 - 3 years.

by a current (last month or quarter) selfie. I personally think twice a year pro shoots are an expensive overindulgence if you haven't changed much. A few selfies every quarter would augment pro shots that are 12 -18 months old pretty well, IMO.

As a provider I'll have everything from only brand new (1-2onths old) to a mix of new and some older ones if my hair and body match my current look (I haven't been doing this enough years to change my face, so it's only if I gain or lose weight).  
I model as well so my hair and body must stay relatively consistent.
I've had 3yo photos up and everyone said I looked like my photos but better in person.   Currently they're all brand new.
I think it's just about giving an accurate portrayal.