There is a world of difference between doing something for the first time, doing it a second time, doing it regularly, and doing it as a professional.
The first time is full of uncertainty: it might involve going to a new place (Where? How do I get there? Where do I park? Who should I talk to for help?) getting hold of new tools and learning their use, acquiring the feel for a new set of materials and the knack of a new process (or rather, doing a process for which you’re yet to develop the knack). It often involves learning to see and (at least partially) overcome a whole set of factors and limitations of which you were previously only vaguely aware. You’re surprised by what is easy and what is hard. You are tentative when you should be forceful, and too firm where a light touch is needed. Things get broken. You run out of key materials, while others are barely used. Time, effort and materials are wasted.
The second time is roughly twice as easy and takes half the time… except that you’re likely to run into a second set of common complications and problems that you didn’t encounter the first time round.
When you do something regularly, there’s an element of routine: you know the territory and the tools (you might even have a few new and specialised ones), you have a degree of technique, and you have a good sense of the steps in the process. It may still take you time to assemble your materials and prepare for work, but you know what you’re doing and how long it should take. You spot problems in advance and know how to deal with most of them. Things are less fraught, more matter-of-fact.
Working as a professional – or even a journeyman – is different again. You do the thing all the time. The tools are in your belt, or in the van. You set up quickly. Your movements are assured. It looks quick and easy (“Did I pay her all that money for less than an hour’s work?”), complications are the exception, and the results are consistently good.
The master – a professional with training and years of practice – is on another level entirely.
It’s helpful to remind yourself what level you’re working at. You can’t specialise at everything, so you’ll need to allow for most things to take more time (twice the time?) and effort and to cost more money than you first expect.
Alternatively, you might seek the services of a professional.