Occasionally I do fly helicopter and fixed wing in the same day. I do use the prestart and pretakeoff checklist in the helicopter, as I don't fly it often enough to be in "flow" with it, and I don't need the distraction of catching something up later.
When I do transition training to amphibians, I do not make a big deal about checklists, instead, I make a very big deal about the configuration assurance mentioned by Pilot DAR. If you're changing the phase of flight, your brain, without the aid of paper better have the configuration correct. It's all memory items! If you want to add time in there to put the next phase of flight on hold for a few seconds to use the checklist, I can't knock that, but it will be just that, a checklist - everything better have been correctly set and confirmed already - because you know what it should be from your training and skill, and your brain reminds you to check.
Our culture does not allow for abandoning checklists entirely, but I will openly relegate them to their intended role - to aid the pilot in confirming that all required actions have been done. It is not a "to do" list, and I won't solo a pilot who relies on it that way...