The mistake I see most often is a plan built on a map. Canggu to Ubud looks like nothing. On a Friday afternoon it is two hours. Ubud to Lempuyang looks reasonable. It is not, if you also want to be back for dinner in Seminyak.
The three ways people move
A scooter is the cheapest and the most fun, and it is also how most tourists end up in Sanglah hospital. If you ride at home, ride here. If you have never ridden, Bali traffic is not the place to learn, whatever the rental shop tells you. You need an international licence with a motorcycle endorsement, or your travel insurance will not pay.
Ride hailing apps work in the south and are cheap. In Ubud and parts of the south you will find areas where drivers cannot pick up, because the local transport cooperative protects its own work. That is not a scam, it is a local agreement, and arguing about it gets you nowhere.
A private car with a driver is what most people end up on for the long days. Ten hours, you set the route, and the cost splits across the car instead of per person.
How to build a day that works
Pick one region per day. North or east or the islands, not two of them. Leave before seven if a famous place is on the list. Eat where we are, not where you planned to eat, because two hours of backtracking for a restaurant is two hours you do not get back.
And keep the last afternoon of your trip free of anything that involves a boat.
Traffic honesty
I will tell you when something does not fit. It costs me a booking and saves you a bad day, and people come back for exactly that reason. If you want Lempuyang, Tirta Gangga and a waterfall in the north in one day, I will say no and then show you what does fit.
