Is it better to have only one item that needs level upgrade, thus getting all of the heat, or is the heat given to as many items as you have to the same measure: only one Item at level 1 ( all other armaments at lvl 10) thus getting 100% of acquired heat (gaining level increase sooner); or five items at various levels sharing 100% of energy at 20% each, or five items all getting the same measure (100%) of acquired heat.
Thanks.
I have tried different approaches, but I haven't seen much difference if only one item or five in terms of lvl speed increase.
Regardless of how you do it your gear will, in theory, all reach level 10 at the same time. If you decide to level piece by piece you will still have to spend extended time getting heat for each individual piece. You also lose out on any heat gathered above the level 10 cap. On the converse if you level them all at the same time while it may seem like they are leveling slower you are still getting the exact same heat you would if you were doing it solo, just spread between all pieces. This leaves more room to get that extra sliver once some or all of your things hit 10.
In short: it doesn't matter.