One limit is worth stating up front: this page can’t explain why your dressing soaks through at every change. But a lot of what’s closely related is clear, and it’s set out below.
If liquid leaks out of the dressing, or if the wound is much more painful than before without a clear reason, it’s strongly recommended that you contact your treating health care professional.
With surgical wounds, you will want to change the dressing sooner if it becomes wet or soaked with blood or other fluids. That covers what to do in the moment, not why it keeps happening.
As for the drainage itself: with an ischemic ulcer, more drainage than before, or drainage that is yellowish or cloudy, is one of the signs of infection to contact a provider about. With a diabetic foot ulcer, extra drainage is a sign in the same way.
How often a dressing should be changed depends on the type of wound and the type of dressing, and some dressings are designed to stay in place for up to seven days. A dressing that’s overwhelmed well before its intended change time is the kind of mismatch the person who chose the dressing would want to know about.
This page can’t tell you whether the amount you’re seeing is expected for your wound. There’s no general measure for that, and guessing at one here would be inventing it.