If you attempt to replace a washer in the water pipe under your kitchen sink, you are already draining your own resources. What you are going through, attempting to do, is futile. You simply do not have the skills of accuracy and precision that 24-hour local plumbers in Katy, TX have. As you can see, they also have time on their side. They will not leave your premises until such time that your plumbing issue has been resolved for once and for all.
And they might want to come back and do more work. Not in any way does this suggest that they have not done a proper job first time round. It is so unlike what you may have done after attempting to replace the washer in the pipe under your kitchen sink. Or not done. After all, would you be crawling under the kitchen sink every now and then just to see that there has been no further leaking? Thought so. But they would.
It simply means that they are doing their jobs correctly. You are required to give them a call the moment there is a persistent leak. You do this right away before the leak worsens. After all, your local plumbers are now available on the 24/7 basis. But will they be charging you additional fees for these so-called overtime hours? Not necessarily. Depending on your domestic or commercial circumstances, your plumbing infrastructure, and perhaps how much water you are utilising, you might want to consider taking out a contract with these tradesmen.
Note too that part of a contract could entail regular maintenance inspections across the perimeters of your premises. And when minor repairs are called for, this might also negate the potential for emergency incidents.