In answer to the OPs question, no, I’ve never felt that a regular was taking advantage of me or wasting my time, and I wouldn’t tolerate it if I did, but regularly seeing an SP has certainly been one of the great pleasures of this hobby for me.
But don’t confuse regular with frequent. In my almost 20 years of punting, I have had probably 7 regulars. That is, SPs who I have seen 10 or more times. I only punt about 18 times a year now, and rarely see the same SP more frequently than once every 6 to 8 weeks, and there are presently, Covid notwithstanding, three women I see regularly. One of them I have seen almost 100 times over 13 years!
So, what’s the attraction? I like to take my time, with lots of foreplay, and I have a penchant for submissive ladies. Nothing too extreme – a bit of bondage and sensory deprivation – certainly no pain beyond, perhaps, nipple clamps and the like, and, in addition to those SPs who offer that service, I have successfully ‘introduced’ at least three ladies to these games. Not only that, but I have indulged in a bit of role-reversal, including receiving a (small!!) strap-on, hot wax play and, more recently, a TENS machine. None of this would I have contemplated without intimate knowledge of the lady concerned, and that can only be achieved through regular meetings.