Do humans need food to live and grow?
Orchids need food but need very little. This is why you do not see big differences.
In humans, the failure to feed a child enough food or the wrong types is recognized as a medical condition called 'failure to thrive'. It does not kill the children, but you will find a 10 year old no larger than a 6 year old. Then there are all kinds of related medical problems that will haunt the child for the rest of its life, both mental and physical. 'Failure to thrive' is considered child abuse.
Orchids certainly fail to thrive when not feed. It is not noticeable to you because you do not have standards against which to compare.
We have a couple of growing projects in the forum. In the Hybrid project I am keeping a control set of plants. After only a few months I am seeing big differences in the condition of my control plants and the slower growth of the members.
I posted two pictures of a control plant only two months difference in this post
Update on Epi. Mabel Kanda, Bc. Little Stars and Blc. Haleahi Sunbow
Have any of your plants shown this much growth in the year without food?
If you do not have time use 6 month slow release fertilizer and in seconds a plant is done for six months.