I have had many Dommes use this to extend the session/service experience and own a device (cb6000). Some Dommes get a nice rush out of having that extended control and power over me. Some are really doing it as a way to provid "extra value" to me as a client. Most importantly in all these scenarios is that I only communicate about the service in a limited and agreed upon way.

To put it in perspective, chastity is not a fetish of mine. Instead it is categorized on my play list as "Things that I don't enjoy just for themselves, but do enjoy as service to a Mistress who enjoys having me do them" (yes, I do actually have a list of all major fetish activities that is sorted into 6 different categories that I provide to Dommes before we play). I also have a physical anomaly that makes wearing a chastity device an issue because after about a day in one, it literally slides off of me (this process can be extremely painful as my balls get crushed while they slide through it, so not having access to the key is a hard limit and long-term chastity is out of the question). Having said all of that, I have had many Pro Dommes do this in different ways:

Scenario 1 - I have been ordered to wear it for several days prior to a session. This has occurred with a couple of different Dommes. At first, they generally want a photo showing it on (this is past a hard limit so I refuse this request) but they do trust that I will do as asked both in and out of session and I do ask for permission if I need to remove or reset the device.

Scenario 2 - I have been ordered to wear it for several days at some random time in between sessions (usually after I have said something "lovingly disrespectful" to the Domme when we text/talk... I am not a SAM, but I am a smartass by nature and love to make people laugh so when I am not in active service I do "tweak the noses" of Dommes that I both serve and am also friends with). Again, Dommes prefer pictures, usually with numbered tags rather than locks but they trust me to do something unless I object and tend to know I am doing it because of "progress reports" about whether I need to reset or not and some whining that they tend to sadistically enjoy.

Scenario 3 - I been put in one (both mine and a Domme's birdcage device) by traveling Dommes while I was staying with them (or they were staying with me, depending upon how you look at it). This was part of my personal service to them and generally when I prove to them that I am not full of it about the damn things falling off.

Scenario 4 - I had one Domme who ordered me to bring it with me (I see her when I travel to her city) then ordered me into it as soon as I checked into the hotel (our session was a couple of days away). I was then to put the key in an envelope, take it to the front desk and leave it for her to come pick up at her leisure. Unfortunately, because of the slippage issue, I told her I had to have a copy of the key or she would have to commit to running over when there was an issue, so she dropped the idea. I even offered to have her come to the room and set the combination on the safe but instead she just had me put it on a few hours before the session (well within my comfort range) and bring the key with me to the session.

Scenario 5 - Not sure if this is applicable, but figured I would throw it in. Chastity without the device. Some Dommes have a no-touching rule for a certain period before a session (3-7 days). Others will order me to edge myself multiple times a day until the session (again usually 3-7 days) but not to orgasm (usually I am required to do this while thinking about her and our past play or looking at her pictures/video). Both are obviously on the honor system but I usually have to text or email a very short report that I have done the task when edging for her (short being the operative word, because I don't know if it comes across here but I can get very "wordy" when writing >:-) ). Punishment if I fail may be something extreme (or nothing at all because of how truthful and apologetic I am if it happens). This works because I am not a SAM (I don't enjoy pain), the Domme knows me well enough to trust that I tell the truth and I appreciate the opportunity to serve outside of the session.

So... To make a short answer long (my specialty by the way), yes... I have had this done quite often with no "extra charges" by the Dommes involved. Probably because if it was my choice, I wouldn't be doing t to begin with.