No, you don't get to say "both" - if given the opportunity to choose quality work versus having a happy customer, will you make that choice?
Customers try to make adjustments for their convenience. These proposed changes often sound something like this
can we do it in two separate appointments?
can we do this while still using the device?
can you do this after hours?
what if we do this ourselves and call you if there are problems?
we can't be down for that long
What do these requests do to your comfort level? Your empathy may be so high and unregulated that you just assume you'll have to "make do" with whatever works best for the customer.
Surgeons don't let you stay awake for procedures requiring anesthesia. Car mechanics don't let you into the shop while they're working. IT pros, however, often accommodate customers, not stopping to think if the change is actually going to increase risk or discomfort for them or their client.
In some cases you'll upset your customer by insisting on doing work in such a way that guarantees quality. You have a choice: put their happiness first, or put quality first.
In few cases is it going to be worth sacrificing the quality. They may seem happy initially if you accommodate them, but if the quality proves to be an issue down the road, they'll almost certainly blame you, or offer a "well if you told me that would happen I wouldn't have wanted you to do it" excuse.
Quality creates happiness. If they're unhappy because you're insisting on whatever you need to ensure the quality work, that's a communication challenge, and one that requires ample discussion before you go any further.