Empress Zhangsun said, "From the fourth to the eighth year of the Zhenguan era, His Majesty spent several months traveling outside the capital every year." This is indeed based on historical records.
"Old Book of Tang, Annals of Emperor Taizong":
In the fourth year, winter, tenth month, on the day Renchen, he visited Longzhou and granted amnesty to Long and Qi prefectures, exempting them from taxes for one year. On the day Xinchou, he hunted at Guiquan Valley. On the day Jiachen, he hunted at Yulong River, personally shooting a deer which he presented at the Great Peace Palace. On the day Jiazi, he returned from Longzhou.
In the fifth year, twelfth month, on the day Renyin, he visited the hot springs. On the day Guimao, he hunted at Mount Li. On the day Bingwu, he bestowed silk upon the elderly of Xinfeng in varying amounts. On the day Wushen, he returned from the hot springs.
In the sixth year, third month, on the day Wuchen, he visited Jiucheng Palace. ... Tenth month, on the day Yimao, he returned from Jiucheng Palace. (This year, he stayed at Jiucheng Palace for seven months.)
In the seventh year, summer, fifth month, on the day Guiwei, he visited Jiucheng Palace. ... Winter, tenth month, on the day Gengshen, he returned from Jiucheng Palace. (This year, it was five months.)
In the eighth year, third month, on the day Gengchen, he visited Jiucheng Palace. ... Winter, tenth month, on the day Jiazi, he returned from Jiucheng Palace. (This year, he enjoyed another seven months of recuperation—what a blissful, publicly funded leisure trip!)