Like driving in a busy city, Flying an Aircraft is a high workload....Unfortunately, when you're overloaded up there, there isn't a side-road to sneak off to and get your head together.
As you have been told, you need enough constant, regular practice to make basic flight-skills automatic.
When all that's second nature, you'llhave reserve mental capacity to do the "different" things...like map-reading, talking to different people on the radio, matching terrain and map,keeping the correct height, etc. etc.
And if you were to have a malfunction / engine failure would you cope, with minimal stress, or freeze into a blind funk?
Sounds like your instructor is trying to make sure you stay alive long enough to complete the course
It's a good suggestion to save a rake of cash as a cushion, so you can fly more frequently, in a block, when costs exceed income.
I note you say you intend to do a more intense period of learning.....read -up training books and practice nav. weather recognition,radio calls etc so you KNOW. the what's whys and hows.
good luck!