In recent years more and more research has been coming out showing that higher frequency training is more effective (in about 75% of the population) then low frequency (ie, single body part per week).
high frequency is simply hitting body parts multiple times per week, so instead of chest once per week on Monday, you'll hit it 3x per week. BUT this does not mean you'll do 3 times the volume (thats a mistake a lot of people make). If you were used to doing 18 sets for chest on your once per week chest day , when you change to high frequency you don't do that same 18 sets workout 3 x per week , rather you break it down and each session is only 6 sets . so your spread the volume out.
a lot of guys want to give high frequency a try, but they don't know how to set up the programming. again they usually end up way over doing the volume and they find themselves having to train 7 days per week with no rest days in order to be able to meet that 3x per week each body part goal
so heres just an example of how to set up a high frequency program that allows for rest days and does not over do the volume
phase 1 - heavy compounds 5-10 rep range (5 working sets per)
day 1 - chest, front and side delts, triceps, quads
day 2 - back, traps, rear delts, biceps, hamstrings
day 3 off
phase 2 - isolation and metabolite training 15-20 rep range (7 working sets per)
day 4 - chest, front and side delts, triceps, quads
day 5 - back, traps, rear delts, biceps, hamstrings
day 6 - whole body touch up work, and active recovery mainly just getting a pump and blood flow (2 working sets per)
day 7 off
all your basis are covered.. you have 2 rest days per week. you have just enough volume (14 working sets per week). and your hitting each muscle group 3x per week with high frequency..
your also getting in your lower rep range heavy compound work for all muscle groups in phase 1,, but also able to get in your lighter weight pump sets and intensifiers (like drops sets) in phase 2. and again plenty of room for rest and recovery.
this is just a rough example of how to set up a high frequency program. you can get "fancy" and custom tailor things to your needs,, perhaps you want to hit chest 3x per week, but only want to hit hamstrings 2x per week, and maybe arms 4x per week. you can do that. or perhaps you only want a weekly volume of 10 sets per week for quads, but 14 sets per week for shoulders, no prob just tweak things where needed.
you can also add other programming strategies into this program as well , like
RIR based progressions (RIR = reps in reserve)
Intensity based progressions . in phase 1 is where you can keep a log book and progress by adding weight to the bar
RPE based progressions (RPE = rate of perceived exertion)
you can add in low volume DC style training , HIT training, or high volume training .. rest pause, drop sets, super sets, muscle rounds , etc..
none of these things are going to mess up the high frequency basis. you may have to switch things around a bit to make a DC or HIT style training work (eg. your likely not going to do heavy bench press, heavy squats, heavy shoulder press, all on the same day.. you may need to break things up a bit).
you can also mix in 2 a day training with this kind of split ..
so in phase 1 day 1 for example -- you'll hit chest and shoulders in the AM workout and quads and triceps in the PM workout
lots of possibilities, you just got to think outside the box (the bro split box that is)