I don't use those doses but it wouldn't be hard in regards to injections. You have 250-300mg/ml test/deca/eq so for an off season cycle 3g would be approx 10ml per week. Even just 3 x 3ml shots covers 9ml so a 4th would be 12ml. Even if you were to do 2ml max if you done 1 per day that is 14ml per week so could be as much as 4.2g's if using 300mg/ml. For really high doses 3ml of 300mg/ml everyday would be 6.3g's per week showing how easy it is to get high. For anyone with any sort of commitment/drive they could do that easily. As long as you don't have bad gear taking 2-3ml shots shouldn't cause any pip. I personally would never inject more than 3ml of aas in one shot and for certain shots my max is 2ml because of the compounds/esters used.
Where it does become more difficult would be when using mainly short esters that are 100mg/ml but even with those you could add them to long estered shots. If you done 2ml at 100mg/ml and added 1ml of 300mg/ml that is 500mg per inj so 1 shot daily is 3.5g per week. Again it takes commitment but 1 injection per day isn't hard for anyone committed. 7 injs per week could be done in even 2 muscles (glutes and delts) without any issues but I would recommend rotating things more and you have lats, quads, arms etc. For me certain short estered gear can sting a tiny bit especially at 1ml but you can pick compounds (plus brands, carrier oils, solvents etc) that suit you best and again rotation so never hitting that spot more than once weekly. Test p is one example of short estered gear that can cause some issues but if mixed with gear that doesn't it will improve matters.
All aspects of bodybuilding can be hard and injections are no different. Those complex drug protocols with high doses are hard work and for some the hardest part of bodybuilding. Again though even using high doses can be done fairly easily if you are willing to do 1 shot daily. Some guys out there are injecting themselves 10 times daily. I have heard of guys doing 50 injs some days it can be that over the top. Even running 3g per week you would/should never have to embrace lumps. The guys who have bad lumps usually have them because they inject the same spot over and over. It's easily done though and I have been the same injecting my glutes over and over because they are easy and it becomes routine.
So it's quite simple you pick products that don't cause you pip, you are willing to inject frequently (4+ times per week) and you rotate injections sites (learn to inj multiple muscles correctly).