Welcome to the forum. Stefan Isler "Lava Flow" is an oncidium we grow, bloom and sell often. It is really easy. Please understand that everyone's conditions are different, so your options will vary slightly depending on who gives you the advice. We grow in a green house and do not have the space or time to watch individual plants until they begin to shrivel. All of our oncidiums are grown in bright light (which causes slight sun speckles in some foliage) and are fertilized weakly -- weekly. During the winter we water the oncids once a week. During the summer on average it is twice a week, sometimes more if temps are near 100. (Arkansas).
Your current location (South Bay Window) is an excellent spot to grow your "Lava Flow". I suggest keeping to your original watering and fertilizing schedule. If you have been successful with phals and paphs, you are doing something right. (Are your plants all in the same type of media? EI: bark? – This will make a difference in how fast they dry out and need to be re-watered.) The oncidiums will need more light than your phals and paphs if your goal it to rebloom. Happy Growing!