They are definitely not lazy even though they often can appear to be.
It's a reason why a Si type benefits from their dual. I think of my SEI friend whose longtime ILE husband would never rush her to get more done, or faster, but instead lets her be herself, and she can take the time with the detail she delights in (and in the end she gets a lot done!). She worked as a nurse early in her marriage but sometime after the first one or two were born (they had four) she worked as mom and homemaker extraordinaire, and truly did a wonderful job taking care of her home and family. Everyone in that family was supported, which just made it a nice family life, and also her ENTp husband was into all manner of things, and working many hours - and he was able to be himself this way, exploring so many interests and juggling many responsibilities - particularly because she was running things so well at home, which she could do with real freedom and self-expression, since he wasn't trying to run her.
Also I would not rush my SLI husband, who does take his time with things and also seems to be doing nothing for certain stretches. But I know what looks like laziness to some is the fact that there is a lot happening inside. He thinks a lot, and he needs to in order to be him. For example we are often working on the house, some big project that has been all thought out and talked out between us as we design it, and then he "begins" the build or construction, at least he said he was beginning, and he seems to be doing nothing. But I always know, he is walking around thinking. When he does get to work, at his own pace, so much has been thought out!