Have you ever had a magical ritual you wanted to perform where the outcome was pretty important to you, and so you wanted everything to go right, but little things that weren't under your control just weren't lining up?
I think everyone has this at some point if they do enough magic.
One of the little details that a lot of people want to include but find to be a pain in the ass to coordinate is planetary hours.
I've often seen where people believe they need to do something during a planetary hour but can't arrange their schedule to do their working to accommodate the planetary hour, or to combine forces with a particular hour on a particular day.
I personally am not very sold on the traditional planetary hour system, at least, not the way it is approached by people who base their use of it on the way it's given in Mathers' version of the Greater Key. In this approach it's just another correspondence, another way to add a particular force to the context of your work. So, while I'm not going to argue in favor or against it at the moment, I will note that as it is simply a means of contextualizing your work within a particular current of force, there are ways around it.
The simplest approach would be some invocation of the planet, like through the Lesser Hexagram Ritual, or through reciting the appropriate Orphic Hymn.
Some people might not like this because it's just a way of ritually setting the space, where the hour is a fixed condition of the environment.
So let's look at another way. We can approach the problem hierarchically like we do in spirit magic. If we want to go a rung above the planetary force, then we would call upon the zodiacal force. The zodiac are generative, the planets and metals are reflective/manifesting, and the elements are producing or manifesting. If we start with the zodiac that determines the chain of manifestation going down into the planets.
The zodiac signs have ruling and mystical planets, but more to the point of an actual fixed condition of reality, the planets sit within regions of the sky mapped by the zodiac. Agrippa's description of the influence of the stars and planets relates to their radiance and their placement. So by invoking the planetary force based on its position in the sky we entreat the source of radiance and the placement while working with our actual environment.
Doing this is actually incredibly simple and can be added before any ritual easily.
Each zodiac sign has an element and a ruling planet. Before your ritual go to each quarter and trace the sign of the ruling element and planet for the sign in which the planet pertaining to your ritual resides at the time your ritual is beginning. Therefore, if you are doing a ritual of Mars and Mars is in Libra at the time of your ritual you would go to each quarter, and trace a symbol of Air, a symbol of Venus, and call upon Zuriel. In each quarter, seal the invocation with the sign of the cross and the seal of the zodiacal sign. Your ritual is now occurring within the light of the sign in which your planet resides, and thus, you and the planet are within the same space.
Even rituals which are defined primarily by the planetary hour, such as Trithemius's Art of Drawing Spirits into Crystals, can be set and determined using this opening.