Solution : https://service.sap.com/sap/support/notes/37844 (SAP Service marketplace login required)
Key words : 
prerequisites preconditions large document amount lock situations, -> rf_beleg -> number ranges -> display intervals -> interval ->, respective number range object rf_beleg, number range object maintenance, additional key words fb01, large document amount, number range object, document numbers centrally, ascending time order, lock situations
Related Notes : 
       
| 179224 | Doc.no.assignment for unbuffered number ranges | 
| 175047 | Causes for FI document number gaps (RF_BELEG) | 
| 158143 | Change current number for buffering in local file | 
| 145092 | Tuning in billing and settlement | 
| 130295 | ASSIGN_LENGTH_0 in LSNR3F01 LOCAL_ENTRY_EXISTS | 
| 76016 | Performance: RFBIBL00, RFBIDE00, RFBIKR00 | 
| 62077 | Info: Internal number assignment is not continuous | 
| 23835 | Buffering RV_BELEG / Number assignment in SD |