If you need 1 TPS to have constant turning, then your brain has not been conditioned to look ahead at all. Needed 1 TPS for look ahead is
great reason to practice at 1 TPS.
What does a musician do when they are making mistakes in a piece of music? Speed up and hope for the best? Of course not, they slow down to a speed at which they can really pay attention to what they are doing. They use the advantage of slower movement to practice efficiency and see where the problems are. Playing at a slower speed allows the musician to clearly think about what is coming up next, and practice the movements, transitions, and musical aspects (dynamics, vibrato, etc.) cleanly. If they were to not slow down and continue practicing fast, they would not be able to do these things and would not improve at them.
The learning rule of thumb: Practice is just the method you use to gain experience. If you are not experiencing the thing you want to practice, you're not practicing it. If you want to look ahead, look ahead. Even if that means 1 TPS.
A more blatant example would be learning 1 look OLL from 2 look. It doesn't work like video games. How many times do you have to solve a cube with 2 look OLL before the experience bar in your head fills up and you magically know 47 new algorithms? That's kind of a stupid question. You can cast magic missiles all day in an RPG and until you level and get the next rank of a completely different spell, like fire ball or something. Do one thing, improve at something else. That's video games. If you were to cast magic missiles all day in real life, you would only get better at magic missiles. If you want to learn 47 new algorithms, you need to experience them one by one over a long period of time until that experience accumulates and forms a new ability. If you want to look ahead, you need to experience it at a slow speed until you gain enough experience to do it faster, then faster, and so on. Same goes for finger tricks, new F2L tricks, cross solutions and execution, scramble sight reading, changing color scheme, becoming color neutral, learning block building, and any other aspect of cubing.
Your goal should always be to experience the thing you want to improve at. How do you experience doing something you cannot yet do? Sacrifice something so that you can, like speed. Slow down so that you can experience looking ahead for real, and let your speed come back naturally as you practice.
So over the past few days...
Try a few weeks instead. Going from no look ahead to sub-20 with look ahead does not happen in a few days. Just be patient.