TO prove my point about how useless heavies are the USSR only made 93 PE-8s most of their bombing was done by mediums and IL-2s and it worked proving the idea of a 4 engine heavy redundant
The 93 PE-8s used something like 4 different engine setups and some of the engines were a bit lacking in reliability, to put it mildly.
They used engines from Mig-3s, at least one type of Diesel engine (truly horrible reliability) and near the end M-82 engine like the LA-5 used. It also over 4 years to build the 93 planes so number available for any one raid were very small.
The PE-8 was an old (first flew in 1936) bomber with a series of unsuitable engines due to the Soviet lack of capabilities or attempts to over reach.
The medium bombers consisted of over 5,000 IL-4, some lend lease B-25s, and a few others.
IL-2s did very little bombing of anything except tactical targets. IL-2s were certainly NOT going bomb targets in Poland until the front lines had nearly reached Poland let alone Germany.
If the Soviets had "streamlined" their forces to use the IL-2 and not built the PE-8 and IL-4 it would have made the German defenses much easier. More fighters could be moved to closer to the front lines and more AA guns moved closer and/or fewer AA guns built and other types of artillery built.
Some goes for the German using only JU-88s. You are automatically reducing the area/range you can effectively strike at and making your enemies defense problems simpler.