5's are best. They are hard, but they are the most profitable. It's probably time to start listening to your body and finding a baseline to work from instead of following a written program. If you get too far away from 5's, you're not going to build much more strength over the long haul.
Just a suggestion to you instead of programming........
At our gym, we train up to a single heavy set of 5 one week and a heavy triple the following week. Whatever the weight is, it makes us work hard on all reps but the last rep of each set should have us wondering why we came to the gym that day. All reps must be done with good form. If not, lower the weight. Having good form in training is more important than the weight.
We typically work up to a heavy single every 6 weeks or so; not a max single. I place a lot of emphasis on controlling the weight.
Personally, not a fan of Sheiko or Smolov. Too much volume and aimless training. It's just a bunch of sets and reps like any program that has nothing to do with you.
Just to give you an idea of what working up to a heavy set of 5 is:
135x8 225x2x3 315x3 365x1 405x1 425x5. You don't need to do 5's all the way up. Getting stronger is more about intensity than volume in the main lifts.
For assistance, find something that mirrors the lift you did. If it's deadlift, maybe some block pulls or deficit pulls or good mornings for a few sets. Add in a slingshot for bench work. Pause squats after squatting....etc....Then maybe one or two isolation exercises afterwards for very light weight and high reps.
Give it a shot. This method has made me a lot stronger over the long haul without injury.
Advancing in this program can be done a couple different ways. I typically like to do a rep max with my working weight. If I can do it for more than 6, I bump the weight up. The other way is if the 5 rep set is feeling lighter each week, I bump the weight up.
You can also do rep max PR's as a way to change things up. If the working weight is typically 425x5, drop down to 365-405 and try for a rep PR once in a while to break up the training.