Experimenting in 3 ways.
1. What I did was look for a comparable deck in my collection--say the Pagan Tarot. Then I chose one a pull of the same cards, using the same headings and looked at what I was thought the cards said, with a brief look at the meanings in my book.
I chose the same spread in the computer generated site and compared.
2. In one volunteer reading example, the questioner was confused but need some guidance. I don't charge, being someone in practice, so the questioner understands that I am learning. The questioner actually chose a spread and a deck online---the fact that they had an online spread to look at actually helped shape a question for me to pull on. The questioner asked me to read along the lines of the same spread in a comparative card pull. I had no idea what the online reading said, although I did find out the chosen deck online was one of the 22 majors only.
The questioner did say soon they were buying a certain deck that I had, so I actually did a reading from that deck manually. It turns out that this deck gave an interesting reading to the questioner in some ideas and guidance. I know this sounds kind of vague, but the original question was very private, so I'm not naming the decks involved.
3. I found that the meanings of the separate decks were actually provided by the author, so there's a different feel to each pull. The Pagan Tarot is very different from the Black Flamingo or Blue Moon deck...that's why I find this a surprising, but interesting variety for comparing my manual spreads.
If you do readings for others, they might also find this helpful to guide you to a spread that helps them shape their question or help them interact with their own cards when you aren't there to talk to them about their fine-tuning questions from your general reading. By the way, you are the second person to tell me in terms of free readings, this seems different than getting a canned reading from other computer-generated card pulls.
What I really like is the website also allows you to link to their site if you want to give a nice freebie...and the decks are very nice, as they are all independents, as far as I know.
Mari