I would not recommend deliberately aiming for symptoms of excess, then dialling back a bit.
The target level for each individual depends on her own physiology and treatment objectives.
Some HRT users (and prescribers) are seeking only palliation of vasomotor symptoms. This can be achieved with very low starting doses titrated to symptom relief.
Others like me choose to aim for physiological replacement, approximating the average estradiol levels across a natural menstrual cycle with the exception of the ovulatory peak, and higher than the early follicular phase as most women don't feel their best during menstruation.
I will personally be maintaining a plasma level of 400-500pmol/L which I know from having had bloods done premenopausally that I thrive at, and this also guarantees bone protection in as far as anything in life can be guaranteed, however I will also get a DEXA every 5 years.
Should new evidence emerge regarding optimal levels for other health outcomes I will be very interested to read this however doses used in clinical practice today are well below the therapeutic doses of the 1990s, hence outcomes for chronic disease prevention in the post WHI era have been disappointing.